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Message-ID: <4df04b840701222108o6992933bied5fff8a525413@mail.gmail.com>
Date: Tue, 23 Jan 2007 13:08:25 +0800
From: "yunfeng zhang" <zyf.zeroos@...il.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2.6.20-rc5 1/1] MM: enhance Linux swap subsystem
re-code my patch, tab = 8. Sorry!
Signed-off-by: Yunfeng Zhang <zyf.zeroos@...il.com>
Index: linux-2.6.19/Documentation/vm_pps.txt
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.19/Documentation/vm_pps.txt 2007-01-23 11:32:02.000000000 +0800
@@ -0,0 +1,236 @@
+ Pure Private Page System (pps)
+ zyf.zeroos@...il.com
+ December 24-26, 2006
+
+// Purpose <([{
+The file is used to document the idea which is published firstly at
+http://www.ussg.iu.edu/hypermail/linux/kernel/0607.2/0451.html, as a part of my
+OS -- main page http://blog.chinaunix.net/u/21764/index.php. In brief, the
+patch of the document is for enchancing the performance of Linux swap
+subsystem. You can find the overview of the idea in section <How to Reclaim
+Pages more Efficiently> and how I patch it into Linux 2.6.19 in section
+<Pure Private Page System -- pps>.
+// }])>
+
+// How to Reclaim Pages more Efficiently <([{
+Good idea originates from overall design and management ability, when you look
+down from a manager view, you will relief yourself from disordered code and
+find some problem immediately.
+
+OK! to modern OS, its memory subsystem can be divided into three layers
+1) Space layer (InodeSpace, UserSpace and CoreSpace).
+2) VMA layer (PrivateVMA and SharedVMA, memory architecture-independent layer).
+3) Page table, zone and memory inode layer (architecture-dependent).
+Maybe it makes you sense that Page/PTE should be placed on the 3rd layer, but
+here, it's placed on the 2nd layer since it's the basic unit of VMA.
+
+Since the 2nd layer assembles the much statistic of page-acess information, so
+it's nature that swap subsystem should be deployed and implemented on the 2nd
+layer.
+
+Undoubtedly, there are some virtues about it
+1) SwapDaemon can collect the statistic of process acessing pages and by it
+ unmaps ptes, SMP specially benefits from it for we can use flush_tlb_range
+ to unmap ptes batchly rather than frequently TLB IPI interrupt per a page in
+ current Linux legacy swap subsystem.
+2) Page-fault can issue better readahead requests since history data shows all
+ related pages have conglomerating affinity. In contrast, Linux page-fault
+ readaheads the pages relative to the SwapSpace position of current
+ page-fault page.
+3) It's conformable to POSIX madvise API family.
+4) It simplifies Linux memory model dramatically. Keep it in mind that new swap
+ strategy is from up to down. In fact, Linux legacy swap subsystem is maybe
+ the only one from down to up.
+
+Unfortunately, Linux 2.6.19 swap subsystem is based on the 3rd layer -- a
+system on memory node::active_list/inactive_list.
+
+I've finished a patch, see section <Pure Private Page System -- pps>. Note, it
+ISN'T perfect.
+// }])>
+
+// Pure Private Page System -- pps <([{
+As I've referred in previous section, perfectly applying my idea need to unroot
+page-surrounging swap subsystem to migrate it on VMA, but a huge gap has
+defeated me -- active_list and inactive_list. In fact, you can find
+lru_add_active code anywhere ... It's IMPOSSIBLE to me to complete it only by
+myself. It's also the difference between my design and Linux, in my OS, page is
+the charge of its new owner totally, however, to Linux, page management system
+is still tracing it by PG_active flag.
+
+So I conceive another solution:) That is, set up an independent page-recycle
+system rooted on Linux legacy page system -- pps, intercept all private pages
+belonging to PrivateVMA to pps, then use my pps to cycle them. By the way, the
+whole job should be consist of two parts, here is the first --
+PrivateVMA-oriented, other is SharedVMA-oriented (should be called SPS)
+scheduled in future. Of course, if both are done, it will empty Linux legacy
+page system.
+
+In fact, pps is centered on how to better collect and unmap process private
+pages, the whole process is divided into six stages -- <Stage Definition>. PPS
+uses init_mm::mm_list to enumerate all swappable UserSpace (shrink_private_vma)
+of mm/vmscan.c. Other sections show the remain aspects of pps
+1) <Data Definition> is basic data definition.
+2) <Concurrent racers of Shrinking pps> is focused on synchronization.
+3) <Private Page Lifecycle of pps> how private pages enter in/go off pps.
+4) <VMA Lifecycle of pps> which VMA is belonging to pps.
+5) <Others about pps> new daemon thread kppsd, pps statistic data etc.
+
+I'm also glad to highlight my a new idea -- dftlb which is described in
+section <Delay to Flush TLB>.
+// }])>
+
+// Delay to Flush TLB (dftlb) <([{
+Delay to flush TLB is instroduced by me to enhance flushing TLB efficiency, in
+brief, when we want to unmap a page from the page table of a process, why we
+send TLB IPI to other CPUs immediately, since every CPU has timer interrupt, we
+can insert flushing tasks into timer interrupt route to implement a
+free-charged TLB flushing.
+
+The trick is implemented in
+1) TLB flushing task is added in fill_in_tlb_task of mm/vmscan.c.
+2) timer_flush_tlb_tasks of kernel/timer.c is used by other CPUs to execute
+ flushing tasks.
+3) all data are defined in include/linux/mm.h.
+4) dftlb is done on stage 1 and 2 of vmscan.c:shrink_pvma_scan_ptes.
+
+The restriction of dftlb. Following conditions must be met
+1) atomic cmpxchg instruction.
+2) atomically set the access bit after CPU touches a pte firstly.
+3) To some architectures, vma parameter of flush_tlb_range is maybe important,
+ if it's true, since it's possible that the vma of a TLB flushing task has
+ gone when a CPU starts to execute the task in timer interrupt, so don't use
+ dftlb.
+combine stage 1 with stage 2, and send IPI immediately in fill_in_tlb_tasks.
+
+dftlb increases mm_struct::mm_users to prevent the mm from being freed when
+other CPU works on it.
+// }])>
+
+// Stage Definition <([{
+The whole process of private page page-out is divided into six stages
+shrink_pvma_scan_ptes of mm/vmscan.c, the code groups the similar ptes/pages to
+a series.
+1) PTE to untouched PTE (clear access bit), append flushing tasks to dftlb.
+---) Other CPUs do flushing tasks in their timer interrupt.
+2) Resume from 1, convert untouched PTE to UnmappedPTE (cmpxchg).
+3) Link SwapEntry to PrivatePage of every UnmappedPTE.
+4) Flush PrivatePage to its disk SwapPage.
+5) Reclaimed the page and shift UnmappedPTE to SwappedPTE.
+6) SwappedPTE stage (Null operation).
+// }])>
+
+// Data Definition <([{
+New VMA flag (VM_PURE_PRIVATE) is appended into VMA in include/linux/mm.h.
+
+New PTE type (UnmappedPTE) is appended into PTE system in
+include/asm-i386/pgtable.h. Its prototype is
+struct UnmappedPTE {
+ int present : 1; // must be 0.
+ ...
+ int pageNum : 20;
+};
+The new PTE has a feature, it keeps a link to its PrivatePage and prevent the
+page from being visited by CPU, so you can use it in <Stage Definition> as a
+middleware.
+// }])>
+
+// Concurrent Racers of Shrinking pps <([{
+shrink_private_vma of mm/vmscan.c uses init_mm.mmlist to scan all swappable
+mm_struct instances, during the process of scaning and reclamation, it
+readlockes mm_struct::mmap_sem, which brings some potential concurrent racers
+1) mm/swapfile.c pps_swapoff (swapoff API)
+2) mm/memory.c do_wp_page, handle_pte_fault::unmapped_pte, do_anonymous_page,
+ do_swap_page (page-fault)
+3) mm/memory.c get_user_pages (sometimes core need share PrivatePage with us)
+
+There isn't new lock order defined in pps, that is, it's compliable to Linux
+lock order.
+// }])>
+
+// Others about pps <([{
+A new kernel thread -- kppsd is introduced in mm/vmscan.c, its task is to
+execute the stages of pps periodically, note an appropriate timeout ticks is
+necessary so we can give application a chance to re-map back its PrivatePage
+from UnmappedPTE to PTE, that is, show their conglomeration affinity.
+
+kppsd can be controlled by new fields -- scan_control::may_reclaim/reclaim_node
+may_reclaim = 1 means starting reclamation (stage 5). reclaim_node = (node
+number) is used when a memory node is low. Caller should set them to wakeup_sc,
+then wake up kppsd (vmscan.c:balance_pgdat). Note, if kppsd is started due to
+timeout, it doesn't do stage 5 at all (vmscan.c:kppsd). Other alive legacy
+fields are gfp_mask, may_writepage and may_swap.
+
+PPS statistic data is appended to /proc/meminfo entry, its prototype is in
+include/linux/mm.h.
+// }])>
+
+// Private Page Lifecycle of pps <([{
+All pages belonging to pps are called as pure private page, its PTE type is PTE
+or UnmappedPTE. Note, Linux fork API potentially make PrivatePage shared by
+multiple processes, so is excluded from pps.
+
+IN (NOTE, when a pure private page enters into pps, it's also trimmed from
+Linux legacy page system by commeting lru_cache_add_active clause)
+1) fs/exec.c install_arg_pages (argument pages)
+2) mm/memory do_anonymous_page, do_wp_page, do_swap_page (page fault)
+3) mm/swap_state.c read_swap_cache_async (swap pages)
+
+OUT
+1) mm/vmscan.c shrink_pvma_scan_ptes (stage 5, reclaim a private page)
+2) mm/memory zap_pte_range (free a page)
+3) kernel/fork.c dup_mmap (if someone uses fork, migrate all pps
+ pages back to let Linux legacy page system manage them)
+
+When a pure private page is in pps, it can be visited simultaneously by
+page-fault and SwapDaemon.
+// }])>
+
+// VMA Lifecycle of pps <([{
+When a PrivateVMA enters into pps, it's or-ed a new flag -- VM_PURE_PRIVATE in
+memory.c:enter_pps, you can also find which VMAs are fit with pps in it. The
+flag is used mainly in the shrink_private_vma of mm/vmscan.c. Other fields are
+left untouched.
+
+IN.
+1) fs/exec.c setup_arg_pages (StackVMA)
+2) mm/mmap.c do_mmap_pgoff, do_brk (DataVMA)
+3) mm/mmap.c split_vma, copy_vma (in some cases, we need copy a VMA from
+ an exist VMA)
+
+OUT.
+1) kernel/fork.c dup_mmap (if someone uses fork, return the vma
+ back to Linux legacy system)
+2) mm/mmap.c remove_vma, vma_adjust (destroy VMA)
+3) mm/mmap.c do_mmap_pgoff (delete VMA when some errors occur)
+
+The VMAs of pps can coexist with madvise, mlock, mprotect, mmap and munmap,
+that is why new VMA created from mmap.c:split_vma can re-enter into pps.
+// }])>
+
+// Postscript <([{
+Note, some circumstances aren't tested due to hardware restriction e.g. SMP
+dftlb. So there is no guanrantee in my dftlb code and EVEN my idea.
+
+Here are some improvements about pps
+1) In fact, I recommend one-to-one private model -- PrivateVMA, (PTE,
+ UnmappedPTE) and (PrivatePage, DiskSwapPage) which is described in my OS and
+ the above hyperlink of Linux kernel mail list. Current Linux core supports a
+ trick -- COW on PrivatePage which is used by fork API, the API should be
+ used rarely, POSIX thread library, vfork/execve are enough to application,
+ but as the result, it potentially makes PrivatePage shared, so I think it's
+ unnecessary to Linux, do copy-on-calling if someone really need it. If you
+ agree it, you will find UnmappedPTE + PrivatePage IS swap cache of Linux,
+ and swap_info_struct::swap_map should be bitmap other than (short int)map.
+ So it's a compromise to use Linux legacy SwapCache in my pps. That's why my
+ patch is called pps -- pure private (page) system.
+2) SwapSpace should provide more flexible interfaces, shrink_pvma_scan_ptes
+ need allocate swap entries in batch, exactly, allocate a batch of fake
+ continual swap entries, see memory.c:pps_swapin_readahead. In fact, the
+ interface should be overloaded, that is, swap file should has a different
+ strategy versus swap partition.
+
+If Linux kernel group can't make a schedule to re-write their memory code,
+however, pps maybe is the best solution until now.
+// }])>
+// vim: foldmarker=<([{,}])> foldmethod=marker et
Index: linux-2.6.19/fs/exec.c
===================================================================
--- linux-2.6.19.orig/fs/exec.c 2007-01-22 13:58:30.000000000 +0800
+++ linux-2.6.19/fs/exec.c 2007-01-23 11:32:30.000000000 +0800
@@ -321,10 +321,11 @@
pte_unmap_unlock(pte, ptl);
goto out;
}
+ atomic_inc(&pps_info.total);
+ atomic_inc(&pps_info.pte_count);
inc_mm_counter(mm, anon_rss);
- lru_cache_add_active(page);
- set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
- page, vma->vm_page_prot))));
+ set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(page,
+ vma->vm_page_prot))));
page_add_new_anon_rmap(page, vma, address);
pte_unmap_unlock(pte, ptl);
@@ -437,6 +438,7 @@
kmem_cache_free(vm_area_cachep, mpnt);
return ret;
}
+ enter_pps(mm, mpnt);
mm->stack_vm = mm->total_vm = vma_pages(mpnt);
}
Index: linux-2.6.19/fs/proc/proc_misc.c
===================================================================
--- linux-2.6.19.orig/fs/proc/proc_misc.c 2007-01-22 13:58:31.000000000 +0800
+++ linux-2.6.19/fs/proc/proc_misc.c 2007-01-22 14:00:00.000000000 +0800
@@ -181,7 +181,11 @@
"Committed_AS: %8lu kB\n"
"VmallocTotal: %8lu kB\n"
"VmallocUsed: %8lu kB\n"
- "VmallocChunk: %8lu kB\n",
+ "VmallocChunk: %8lu kB\n"
+ "PPS Total: %8d kB\n"
+ "PPS PTE: %8d kB\n"
+ "PPS Unmapped: %8d kB\n"
+ "PPS Swapped: %8d kB\n",
K(i.totalram),
K(i.freeram),
K(i.bufferram),
@@ -212,7 +216,11 @@
K(committed),
(unsigned long)VMALLOC_TOTAL >> 10,
vmi.used >> 10,
- vmi.largest_chunk >> 10
+ vmi.largest_chunk >> 10,
+ K(pps_info.total.counter),
+ K(pps_info.pte_count.counter),
+ K(pps_info.unmapped_count.counter),
+ K(pps_info.swapped_count.counter)
);
len += hugetlb_report_meminfo(page + len);
Index: linux-2.6.19/include/asm-i386/mmu_context.h
===================================================================
--- linux-2.6.19.orig/include/asm-i386/mmu_context.h 2007-01-22
13:58:32.000000000 +0800
+++ linux-2.6.19/include/asm-i386/mmu_context.h 2007-01-23
11:43:00.000000000 +0800
@@ -32,6 +32,10 @@
/* stop flush ipis for the previous mm */
cpu_clear(cpu, prev->cpu_vm_mask);
#ifdef CONFIG_SMP
+ // vmscan.c::end_tlb_tasks maybe had copied cpu_vm_mask before
+ // we leave prev, so let's flush the trace of prev of
+ // delay_tlb_tasks.
+ timer_flush_tlb_tasks(NULL);
per_cpu(cpu_tlbstate, cpu).state = TLBSTATE_OK;
per_cpu(cpu_tlbstate, cpu).active_mm = next;
#endif
Index: linux-2.6.19/include/asm-i386/pgtable-2level.h
===================================================================
--- linux-2.6.19.orig/include/asm-i386/pgtable-2level.h 2007-01-22
13:58:32.000000000 +0800
+++ linux-2.6.19/include/asm-i386/pgtable-2level.h 2007-01-23
12:50:09.905950872 +0800
@@ -48,21 +48,22 @@
}
/*
- * Bits 0, 6 and 7 are taken, split up the 29 bits of offset
+ * Bits 0, 5, 6 and 7 are taken, split up the 28 bits of offset
* into this range:
*/
-#define PTE_FILE_MAX_BITS 29
+#define PTE_FILE_MAX_BITS 28
#define pte_to_pgoff(pte) \
- ((((pte).pte_low >> 1) & 0x1f ) + (((pte).pte_low >> 8) << 5 ))
+ ((((pte).pte_low >> 1) & 0xf ) + (((pte).pte_low >> 8) << 4 ))
#define pgoff_to_pte(off) \
- ((pte_t) { (((off) & 0x1f) << 1) + (((off) >> 5) << 8) + _PAGE_FILE })
+ ((pte_t) { (((off) & 0xf) << 1) + (((off) >> 4) << 8) + _PAGE_FILE })
/* Encode and de-code a swap entry */
-#define __swp_type(x) (((x).val >> 1) & 0x1f)
+#define __swp_type(x) (((x).val >> 1) & 0xf)
#define __swp_offset(x) ((x).val >> 8)
-#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 1) |
((offset) << 8) })
+#define __swp_entry(type, offset) ((swp_entry_t) { ((type & 0xf) << 1) |\
+ ((offset) << 8) | _PAGE_SWAPPED })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_low })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
Index: linux-2.6.19/include/asm-i386/pgtable.h
===================================================================
--- linux-2.6.19.orig/include/asm-i386/pgtable.h 2007-01-22
13:58:32.000000000 +0800
+++ linux-2.6.19/include/asm-i386/pgtable.h 2007-01-23 11:47:00.775687672 +0800
@@ -121,7 +121,11 @@
#define _PAGE_UNUSED3 0x800
/* If _PAGE_PRESENT is clear, we use these: */
-#define _PAGE_FILE 0x040 /* nonlinear file mapping, saved PTE; unset:swap */
+#define _PAGE_UNMAPPED 0x020 /* a special PTE type, hold its page reference
+ even it's unmapped, see more from
+ Documentation/vm_pps.txt. */
+#define _PAGE_SWAPPED 0x040 /* swapped PTE. */
+#define _PAGE_FILE 0x060 /* nonlinear file mapping, saved PTE; */
#define _PAGE_PROTNONE 0x080 /* if the user mapped it with PROT_NONE;
pte_present gives true */
#ifdef CONFIG_X86_PAE
@@ -227,7 +231,12 @@
/*
* The following only works if pte_present() is not true.
*/
-static inline int pte_file(pte_t pte) { return (pte).pte_low & _PAGE_FILE; }
+static inline int pte_unmapped(pte_t pte) { return ((pte).pte_low & 0x60)
+ == _PAGE_UNMAPPED; }
+static inline int pte_swapped(pte_t pte) { return ((pte).pte_low & 0x60)
+ == _PAGE_SWAPPED; }
+static inline int pte_file(pte_t pte) { return ((pte).pte_low & 0x60)
+ == _PAGE_FILE; }
static inline pte_t pte_rdprotect(pte_t pte) { (pte).pte_low &=
~_PAGE_USER; return pte; }
static inline pte_t pte_exprotect(pte_t pte) { (pte).pte_low &=
~_PAGE_USER; return pte; }
Index: linux-2.6.19/include/linux/mm.h
===================================================================
--- linux-2.6.19.orig/include/linux/mm.h 2007-01-22 13:58:34.000000000 +0800
+++ linux-2.6.19/include/linux/mm.h 2007-01-23 12:27:56.171419760 +0800
@@ -168,6 +168,9 @@
#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
#define VM_INSERTPAGE 0x02000000 /* The vma has had
"vm_insert_page()" done on it */
+#define VM_PURE_PRIVATE 0x04000000 /* Is the vma is only belonging to a
+ mm, see more from
+ Documentation/vm_pps.txt */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -1166,5 +1169,33 @@
__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma);
+struct pps_info {
+ atomic_t total;
+ atomic_t pte_count; // stage 1 and 2.
+ atomic_t unmapped_count; // stage 3 and 4.
+ atomic_t swapped_count; // stage 6.
+};
+extern struct pps_info pps_info;
+
+/* vmscan.c::delay flush TLB */
+struct delay_tlb_task
+{
+ struct mm_struct* mm;
+ cpumask_t cpu_mask;
+ struct vm_area_struct* vma[32];
+ unsigned long start[32];
+ unsigned long end[32];
+};
+extern struct delay_tlb_task delay_tlb_tasks[32];
+
+// The prototype of the function is fit with the "func" of "int
+// smp_call_function (void (*func) (void *info), void *info, int retry, int
+// wait);" of include/linux/smp.h of 2.6.16.29. Call it with NULL.
+void timer_flush_tlb_tasks(void* data /* = NULL */);
+
+void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma);
+void leave_pps(struct vm_area_struct* vma, int migrate_flag);
+
+#define MAX_SERIES_LENGTH 8
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
Index: linux-2.6.19/include/linux/swapops.h
===================================================================
--- linux-2.6.19.orig/include/linux/swapops.h 2006-11-30
05:57:37.000000000 +0800
+++ linux-2.6.19/include/linux/swapops.h 2007-01-22 14:00:00.000000000 +0800
@@ -50,7 +50,7 @@
{
swp_entry_t arch_entry;
- BUG_ON(pte_file(pte));
+ BUG_ON(!pte_swapped(pte));
arch_entry = __pte_to_swp_entry(pte);
return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
}
@@ -64,7 +64,7 @@
swp_entry_t arch_entry;
arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
- BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
+ BUG_ON(!pte_swapped(__swp_entry_to_pte(arch_entry)));
return __swp_entry_to_pte(arch_entry);
}
Index: linux-2.6.19/kernel/fork.c
===================================================================
--- linux-2.6.19.orig/kernel/fork.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/kernel/fork.c 2007-01-22 14:00:00.000000000 +0800
@@ -241,6 +241,7 @@
tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!tmp)
goto fail_nomem;
+ leave_pps(mpnt, 1);
*tmp = *mpnt;
pol = mpol_copy(vma_policy(mpnt));
retval = PTR_ERR(pol);
Index: linux-2.6.19/kernel/timer.c
===================================================================
--- linux-2.6.19.orig/kernel/timer.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/kernel/timer.c 2007-01-22 14:00:00.000000000 +0800
@@ -1115,6 +1115,10 @@
rcu_check_callbacks(cpu, user_tick);
scheduler_tick();
run_posix_cpu_timers(p);
+
+#ifdef SMP
+ timer_flush_tlb_tasks(NULL);
+#endif
}
/*
Index: linux-2.6.19/mm/fremap.c
===================================================================
--- linux-2.6.19.orig/mm/fremap.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/fremap.c 2007-01-22 14:00:00.000000000 +0800
@@ -37,7 +37,7 @@
page_cache_release(page);
}
} else {
- if (!pte_file(pte))
+ if (pte_swapped(pte))
free_swap_and_cache(pte_to_swp_entry(pte));
pte_clear_not_present_full(mm, addr, ptep, 0);
}
Index: linux-2.6.19/mm/memory.c
===================================================================
--- linux-2.6.19.orig/mm/memory.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/memory.c 2007-01-23 12:47:12.000000000 +0800
@@ -435,7 +435,7 @@
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
- if (!pte_file(pte)) {
+ if (pte_swapped(pte)) {
swp_entry_t entry = pte_to_swp_entry(pte);
swap_duplicate(entry);
@@ -628,6 +628,9 @@
spinlock_t *ptl;
int file_rss = 0;
int anon_rss = 0;
+ int pps_pte = 0;
+ int pps_unmapped = 0;
+ int pps_swapped = 0;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
arch_enter_lazy_mmu_mode();
@@ -672,6 +675,13 @@
addr) != page->index)
set_pte_at(mm, addr, pte,
pgoff_to_pte(page->index));
+ if (vma->vm_flags & VM_PURE_PRIVATE) {
+ if (page != ZERO_PAGE(addr)) {
+ if (PageWriteback(page))
+ lru_cache_add_active(page);
+ pps_pte++;
+ }
+ }
if (PageAnon(page))
anon_rss--;
else {
@@ -691,12 +701,31 @@
*/
if (unlikely(details))
continue;
- if (!pte_file(ptent))
+ if (pte_unmapped(ptent)) {
+ struct page *page;
+ page = pfn_to_page(pte_pfn(ptent));
+ BUG_ON(page == ZERO_PAGE(addr));
+ if (PageWriteback(page))
+ lru_cache_add_active(page);
+ pps_unmapped++;
+ ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
+ tlb_remove_page(tlb, page);
+ anon_rss--;
+ continue;
+ }
+ if (pte_swapped(ptent)) {
+ if (vma->vm_flags & VM_PURE_PRIVATE)
+ pps_swapped++;
free_swap_and_cache(pte_to_swp_entry(ptent));
+ }
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
add_mm_rss(mm, file_rss, anon_rss);
+ atomic_sub(pps_pte + pps_unmapped, &pps_info.total);
+ atomic_sub(pps_pte, &pps_info.pte_count);
+ atomic_sub(pps_unmapped, &pps_info.unmapped_count);
+ atomic_sub(pps_swapped, &pps_info.swapped_count);
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
@@ -955,7 +984,8 @@
if ((flags & FOLL_WRITE) &&
!pte_dirty(pte) && !PageDirty(page))
set_page_dirty(page);
- mark_page_accessed(page);
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ mark_page_accessed(page);
}
unlock:
pte_unmap_unlock(ptep, ptl);
@@ -1606,7 +1636,12 @@
ptep_clear_flush(vma, address, page_table);
set_pte_at(mm, address, page_table, entry);
update_mmu_cache(vma, address, entry);
- lru_cache_add_active(new_page);
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ lru_cache_add_active(new_page);
+ else {
+ atomic_inc(&pps_info.total);
+ atomic_inc(&pps_info.pte_count);
+ }
page_add_new_anon_rmap(new_page, vma, address);
/* Free the old page.. */
@@ -1975,6 +2010,85 @@
}
/*
+ * New read ahead code, mainly for VM_PURE_PRIVATE only.
+ */
+static void pps_swapin_readahead(swp_entry_t entry, unsigned long addr, struct
+ vm_area_struct *vma, pte_t* pte, pmd_t* pmd)
+{
+ struct page* page;
+ pte_t *prev, *next;
+ swp_entry_t temp;
+ spinlock_t* ptl = pte_lockptr(vma->vm_mm, pmd);
+ int swapType = swp_type(entry);
+ int swapOffset = swp_offset(entry);
+ int readahead = 1, abs;
+
+ if (!(vma->vm_flags & VM_PURE_PRIVATE)) {
+ swapin_readahead(entry, addr, vma);
+ return;
+ }
+
+ page = read_swap_cache_async(entry, vma, addr);
+ if (!page)
+ return;
+ page_cache_release(page);
+
+ // read ahead the whole series, first forward then backward.
+ while (readahead < MAX_SERIES_LENGTH) {
+ next = pte++;
+ if (next - (pte_t*) pmd >= PTRS_PER_PTE)
+ break;
+ spin_lock(ptl);
+ if (!(!pte_present(*next) && pte_swapped(*next))) {
+ spin_unlock(ptl);
+ break;
+ }
+ temp = pte_to_swp_entry(*next);
+ spin_unlock(ptl);
+ if (swp_type(temp) != swapType)
+ break;
+ abs = swp_offset(temp) - swapOffset;
+ abs = abs < 0 ? -abs : abs;
+ swapOffset = swp_offset(temp);
+ if (abs > 8)
+ // the two swap entries are too far, give up!
+ break;
+ page = read_swap_cache_async(temp, vma, addr);
+ if (!page)
+ return;
+ page_cache_release(page);
+ readahead++;
+ }
+
+ swapOffset = swp_offset(entry);
+ while (readahead < MAX_SERIES_LENGTH) {
+ prev = pte--;
+ if (prev - (pte_t*) pmd < 0)
+ break;
+ spin_lock(ptl);
+ if (!(!pte_present(*prev) && pte_swapped(*prev))) {
+ spin_unlock(ptl);
+ break;
+ }
+ temp = pte_to_swp_entry(*prev);
+ spin_unlock(ptl);
+ if (swp_type(temp) != swapType)
+ break;
+ abs = swp_offset(temp) - swapOffset;
+ abs = abs < 0 ? -abs : abs;
+ swapOffset = swp_offset(temp);
+ if (abs > 8)
+ // the two swap entries are too far, give up!
+ break;
+ page = read_swap_cache_async(temp, vma, addr);
+ if (!page)
+ return;
+ page_cache_release(page);
+ readahead++;
+ }
+}
+
+/*
* We enter with non-exclusive mmap_sem (to exclude vma changes,
* but allow concurrent faults), and pte mapped but not yet locked.
* We return with mmap_sem still held, but pte unmapped and unlocked.
@@ -2001,7 +2115,7 @@
page = lookup_swap_cache(entry);
if (!page) {
grab_swap_token(); /* Contend for token _before_ read-in */
- swapin_readahead(entry, address, vma);
+ pps_swapin_readahead(entry, address, vma, page_table, pmd);
page = read_swap_cache_async(entry, vma, address);
if (!page) {
/*
@@ -2021,7 +2135,8 @@
}
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
- mark_page_accessed(page);
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ mark_page_accessed(page);
lock_page(page);
/*
@@ -2033,6 +2148,10 @@
if (unlikely(!PageUptodate(page))) {
ret = VM_FAULT_SIGBUS;
+ if (vma->vm_flags & VM_PURE_PRIVATE) {
+ lru_cache_add_active(page);
+ mark_page_accessed(page);
+ }
goto out_nomap;
}
@@ -2053,6 +2172,11 @@
if (vm_swap_full())
remove_exclusive_swap_page(page);
unlock_page(page);
+ if (vma->vm_flags & VM_PURE_PRIVATE) {
+ atomic_dec(&pps_info.swapped_count);
+ atomic_inc(&pps_info.total);
+ atomic_inc(&pps_info.pte_count);
+ }
if (write_access) {
if (do_wp_page(mm, vma, address,
@@ -2104,8 +2228,13 @@
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
if (!pte_none(*page_table))
goto release;
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ lru_cache_add_active(page);
+ else {
+ atomic_inc(&pps_info.total);
+ atomic_inc(&pps_info.pte_count);
+ }
inc_mm_counter(mm, anon_rss);
- lru_cache_add_active(page);
page_add_new_anon_rmap(page, vma, address);
} else {
/* Map the ZERO_PAGE - vm_page_prot is readonly */
@@ -2392,6 +2521,22 @@
old_entry = entry = *pte;
if (!pte_present(entry)) {
+ if (pte_unmapped(entry)) {
+ BUG_ON(!(vma->vm_flags & VM_PURE_PRIVATE));
+ atomic_dec(&pps_info.unmapped_count);
+ atomic_inc(&pps_info.pte_count);
+ struct page* page = pte_page(entry);
+ pte_t temp_pte = mk_pte(page, vma->vm_page_prot);
+ pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+ if (unlikely(pte_same(*pte, entry))) {
+ page_add_new_anon_rmap(page, vma, address);
+ set_pte_at(mm, address, pte, temp_pte);
+ update_mmu_cache(vma, address, temp_pte);
+ lazy_mmu_prot_update(temp_pte);
+ }
+ pte_unmap_unlock(pte, ptl);
+ return VM_FAULT_MINOR;
+ }
if (pte_none(entry)) {
if (vma->vm_ops) {
if (vma->vm_ops->nopage)
@@ -2685,3 +2830,118 @@
return buf - old_buf;
}
+
+static void migrate_back_pte_range(struct mm_struct* mm, pmd_t *pmd, struct
+ vm_area_struct *vma, unsigned long addr, unsigned long end)
+{
+ struct page* page;
+ pte_t entry;
+ pte_t *pte;
+ spinlock_t* ptl;
+ int pps_pte = 0;
+ int pps_unmapped = 0;
+ int pps_swapped = 0;
+
+ pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ do {
+ if (!pte_present(*pte) && pte_unmapped(*pte)) {
+ page = pte_page(*pte);
+ entry = mk_pte(page, vma->vm_page_prot);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ set_pte_at(mm, addr, pte, entry);
+ BUG_ON(page == ZERO_PAGE(addr));
+ page_add_new_anon_rmap(page, vma, addr);
+ lru_cache_add_active(page);
+ pps_unmapped++;
+ } else if (pte_present(*pte)) {
+ page = pte_page(*pte);
+ if (page == ZERO_PAGE(addr))
+ continue;
+ lru_cache_add_active(page);
+ pps_pte++;
+ } else if (!pte_present(*pte) && pte_swapped(*pte))
+ pps_swapped++;
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ pte_unmap_unlock(pte - 1, ptl);
+ lru_add_drain();
+ atomic_sub(pps_pte + pps_unmapped, &pps_info.total);
+ atomic_sub(pps_pte, &pps_info.pte_count);
+ atomic_sub(pps_unmapped, &pps_info.unmapped_count);
+ atomic_sub(pps_swapped, &pps_info.swapped_count);
+}
+
+static void migrate_back_pmd_range(struct mm_struct* mm, pud_t *pud, struct
+ vm_area_struct *vma, unsigned long addr, unsigned long end)
+{
+ pmd_t *pmd;
+ unsigned long next;
+
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ migrate_back_pte_range(mm, pmd, vma, addr, next);
+ } while (pmd++, addr = next, addr != end);
+}
+
+static void migrate_back_pud_range(struct mm_struct* mm, pgd_t *pgd, struct
+ vm_area_struct *vma, unsigned long addr, unsigned long end)
+{
+ pud_t *pud;
+ unsigned long next;
+
+ pud = pud_offset(pgd, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ migrate_back_pmd_range(mm, pud, vma, addr, next);
+ } while (pud++, addr = next, addr != end);
+}
+
+// migrate all pages of pure private vma back to Linux legacy memory
management.
+static void migrate_back_legacy_linux(struct mm_struct* mm, struct
vm_area_struct* vma)
+{
+ pgd_t* pgd;
+ unsigned long next;
+ unsigned long addr = vma->vm_start;
+ unsigned long end = vma->vm_end;
+
+ pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ migrate_back_pud_range(mm, pgd, vma, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}
+
+void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma)
+{
+ int condition = VM_READ | VM_WRITE | VM_EXEC | \
+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | \
+ VM_GROWSDOWN | VM_GROWSUP | \
+ VM_LOCKED | VM_SEQ_READ | VM_RAND_READ | VM_DONTCOPY | \
+ VM_ACCOUNT | VM_PURE_PRIVATE;
+ if (!(vma->vm_flags & ~condition) && vma->vm_file == NULL) {
+ vma->vm_flags |= VM_PURE_PRIVATE;
+ if (list_empty(&mm->mmlist)) {
+ spin_lock(&mmlist_lock);
+ if (list_empty(&mm->mmlist))
+ list_add(&mm->mmlist, &init_mm.mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ }
+}
+
+void leave_pps(struct vm_area_struct* vma, int migrate_flag)
+{
+ struct mm_struct* mm = vma->vm_mm;
+
+ if (vma->vm_flags & VM_PURE_PRIVATE) {
+ vma->vm_flags &= ~VM_PURE_PRIVATE;
+ if (migrate_flag)
+ migrate_back_legacy_linux(mm, vma);
+ }
+}
Index: linux-2.6.19/mm/mmap.c
===================================================================
--- linux-2.6.19.orig/mm/mmap.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/mmap.c 2007-01-22 14:00:00.000000000 +0800
@@ -229,6 +229,7 @@
if (vma->vm_file)
fput(vma->vm_file);
mpol_free(vma_policy(vma));
+ leave_pps(vma, 0);
kmem_cache_free(vm_area_cachep, vma);
return next;
}
@@ -620,6 +621,7 @@
fput(file);
mm->map_count--;
mpol_free(vma_policy(next));
+ leave_pps(next, 0);
kmem_cache_free(vm_area_cachep, next);
/*
* In mprotect's case 6 (see comments on vma_merge),
@@ -1112,6 +1114,8 @@
if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
vma->vm_flags &= ~VM_ACCOUNT;
+ enter_pps(mm, vma);
+
/* Can addr have changed??
*
* Answer: Yes, several device drivers can do it in their
@@ -1138,6 +1142,7 @@
fput(file);
}
mpol_free(vma_policy(vma));
+ leave_pps(vma, 0);
kmem_cache_free(vm_area_cachep, vma);
}
out:
@@ -1165,6 +1170,7 @@
unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
charged = 0;
free_vma:
+ leave_pps(vma, 0);
kmem_cache_free(vm_area_cachep, vma);
unacct_error:
if (charged)
@@ -1742,6 +1748,10 @@
/* most fields are the same, copy all, and then fixup */
*new = *vma;
+ if (new->vm_flags & VM_PURE_PRIVATE) {
+ new->vm_flags &= ~VM_PURE_PRIVATE;
+ enter_pps(mm, new);
+ }
if (new_below)
new->vm_end = addr;
@@ -1950,6 +1960,7 @@
vma->vm_flags = flags;
vma->vm_page_prot = protection_map[flags &
(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
+ enter_pps(mm, vma);
vma_link(mm, vma, prev, rb_link, rb_parent);
out:
mm->total_vm += len >> PAGE_SHIFT;
@@ -2073,6 +2084,10 @@
get_file(new_vma->vm_file);
if (new_vma->vm_ops && new_vma->vm_ops->open)
new_vma->vm_ops->open(new_vma);
+ if (new_vma->vm_flags & VM_PURE_PRIVATE) {
+ new_vma->vm_flags &= ~VM_PURE_PRIVATE;
+ enter_pps(mm, new_vma);
+ }
vma_link(mm, new_vma, prev, rb_link, rb_parent);
}
}
Index: linux-2.6.19/mm/rmap.c
===================================================================
--- linux-2.6.19.orig/mm/rmap.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/rmap.c 2007-01-22 14:00:00.000000000 +0800
@@ -618,6 +618,7 @@
spinlock_t *ptl;
int ret = SWAP_AGAIN;
+ BUG_ON(vma->vm_flags & VM_PURE_PRIVATE);
address = vma_address(page, vma);
if (address == -EFAULT)
goto out;
@@ -676,7 +677,7 @@
#endif
}
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
- BUG_ON(pte_file(*pte));
+ BUG_ON(!pte_swapped(*pte));
} else
#ifdef CONFIG_MIGRATION
if (migration) {
Index: linux-2.6.19/mm/swap_state.c
===================================================================
--- linux-2.6.19.orig/mm/swap_state.c 2006-11-30 05:57:37.000000000 +0800
+++ linux-2.6.19/mm/swap_state.c 2007-01-22 14:00:00.000000000 +0800
@@ -354,7 +354,8 @@
/*
* Initiate read into locked page and return.
*/
- lru_cache_add_active(new_page);
+ if (vma == NULL || !(vma->vm_flags & VM_PURE_PRIVATE))
+ lru_cache_add_active(new_page);
swap_readpage(NULL, new_page);
return new_page;
}
Index: linux-2.6.19/mm/swapfile.c
===================================================================
--- linux-2.6.19.orig/mm/swapfile.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/swapfile.c 2007-01-23 12:31:38.000000000 +0800
@@ -501,6 +501,166 @@
}
#endif
+static int pps_test_swap_type(struct mm_struct* mm, pmd_t* pmd, pte_t* pte, int
+ type, struct page** ret_page)
+{
+ spinlock_t* ptl = pte_lockptr(mm, pmd);
+ swp_entry_t entry;
+ struct page* page;
+
+ spin_lock(ptl);
+ if (!pte_present(*pte) && pte_swapped(*pte)) {
+ entry = pte_to_swp_entry(*pte);
+ if (swp_type(entry) == type) {
+ *ret_page = NULL;
+ spin_unlock(ptl);
+ return 1;
+ }
+ } else {
+ page = pfn_to_page(pte_pfn(*pte));
+ if (PageSwapCache(page)) {
+ entry.val = page_private(page);
+ if (swp_type(entry) == type) {
+ page_cache_get(page);
+ *ret_page = page;
+ spin_unlock(ptl);
+ return 1;
+ }
+ }
+ }
+ spin_unlock(ptl);
+ return 0;
+}
+
+static int pps_swapoff_scan_ptes(struct mm_struct* mm, struct vm_area_struct*
+ vma, pmd_t* pmd, unsigned long addr, unsigned long end, int type)
+{
+ pte_t *pte;
+ struct page* page;
+
+ pte = pte_offset_map(pmd, addr);
+ do {
+ while (pps_test_swap_type(mm, pmd, pte, type, &page)) {
+ if (page == NULL) {
+ switch (__handle_mm_fault(mm, vma, addr, 0)) {
+ case VM_FAULT_SIGBUS:
+ case VM_FAULT_OOM:
+ return -ENOMEM;
+ case VM_FAULT_MINOR:
+ case VM_FAULT_MAJOR:
+ break;
+ default:
+ BUG();
+ }
+ } else {
+ wait_on_page_locked(page);
+ wait_on_page_writeback(page);
+ lock_page(page);
+ if (!PageSwapCache(page)) {
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+ wait_on_page_writeback(page);
+ delete_from_swap_cache(page);
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+ }
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ return 0;
+}
+
+static int pps_swapoff_pmd_range(struct mm_struct* mm, struct vm_area_struct*
+ vma, pud_t* pud, unsigned long addr, unsigned long end, int type)
+{
+ unsigned long next;
+ int ret;
+ pmd_t* pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ ret = pps_swapoff_scan_ptes(mm, vma, pmd, addr, next, type);
+ if (ret == -ENOMEM)
+ return ret;
+ } while (pmd++, addr = next, addr != end);
+ return 0;
+}
+
+static int pps_swapoff_pud_range(struct mm_struct* mm, struct vm_area_struct*
+ vma, pgd_t* pgd, unsigned long addr, unsigned long end, int type)
+{
+ unsigned long next;
+ int ret;
+ pud_t* pud = pud_offset(pgd, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ ret = pps_swapoff_pmd_range(mm, vma, pud, addr, next, type);
+ if (ret == -ENOMEM)
+ return ret;
+ } while (pud++, addr = next, addr != end);
+ return 0;
+}
+
+static int pps_swapoff_pgd_range(struct mm_struct* mm, struct vm_area_struct*
+ vma, int type)
+{
+ unsigned long next;
+ unsigned long addr = vma->vm_start;
+ unsigned long end = vma->vm_end;
+ int ret;
+ pgd_t* pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ ret = pps_swapoff_pud_range(mm, vma, pgd, addr, next, type);
+ if (ret == -ENOMEM)
+ return ret;
+ } while (pgd++, addr = next, addr != end);
+ return 0;
+}
+
+static int pps_swapoff(int type)
+{
+ struct vm_area_struct* vma;
+ struct list_head *pos;
+ struct mm_struct *prev, *mm;
+ int ret = 0;
+
+ prev = mm = &init_mm;
+ pos = &init_mm.mmlist;
+ atomic_inc(&prev->mm_users);
+ spin_lock(&mmlist_lock);
+ while ((pos = pos->next) != &init_mm.mmlist) {
+ mm = list_entry(pos, struct mm_struct, mmlist);
+ if (!atomic_inc_not_zero(&mm->mm_users))
+ continue;
+ spin_unlock(&mmlist_lock);
+ mmput(prev);
+ prev = mm;
+ down_read(&mm->mmap_sem);
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ continue;
+ if (vma->vm_flags & VM_LOCKED)
+ continue;
+ ret = pps_swapoff_pgd_range(mm, vma, type);
+ if (ret == -ENOMEM)
+ break;
+ }
+ up_read(&mm->mmap_sem);
+ spin_lock(&mmlist_lock);
+ }
+ spin_unlock(&mmlist_lock);
+ mmput(prev);
+ return ret;
+}
+
/*
* No need to decide whether this PTE shares the swap entry with others,
* just let do_wp_page work it out if a write is requested later - to
@@ -694,6 +854,12 @@
int reset_overflow = 0;
int shmem;
+ // Let's first read all pps pages back! Note, it's one-to-one mapping.
+ retval = pps_swapoff(type);
+ if (retval == -ENOMEM) // something was wrong.
+ return -ENOMEM;
+ // Now, the remain pages are shared pages, go ahead!
+
/*
* When searching mms for an entry, a good strategy is to
* start at the first mm we freed the previous entry from
@@ -914,16 +1080,20 @@
*/
static void drain_mmlist(void)
{
- struct list_head *p, *next;
+ // struct list_head *p, *next;
unsigned int i;
for (i = 0; i < nr_swapfiles; i++)
if (swap_info[i].inuse_pages)
return;
+ /*
+ * Now, init_mm.mmlist list not only is used by SwapDevice but also is
+ * used by PPS, see Documentation/vm_pps.txt.
spin_lock(&mmlist_lock);
list_for_each_safe(p, next, &init_mm.mmlist)
list_del_init(p);
spin_unlock(&mmlist_lock);
+ */
}
/*
Index: linux-2.6.19/mm/vmscan.c
===================================================================
--- linux-2.6.19.orig/mm/vmscan.c 2007-01-22 13:58:36.000000000 +0800
+++ linux-2.6.19/mm/vmscan.c 2007-01-23 12:39:48.000000000 +0800
@@ -66,6 +66,10 @@
int swappiness;
int all_unreclaimable;
+
+ /* pps control command. See Documentation/vm_pps.txt. */
+ int may_reclaim;
+ int reclaim_node;
};
/*
@@ -1097,6 +1101,443 @@
return ret;
}
+// pps fields.
+static wait_queue_head_t kppsd_wait;
+static struct scan_control wakeup_sc;
+struct pps_info pps_info = {
+ .total = ATOMIC_INIT(0),
+ .pte_count = ATOMIC_INIT(0), // stage 1 and 2.
+ .unmapped_count = ATOMIC_INIT(0), // stage 3 and 4.
+ .swapped_count = ATOMIC_INIT(0) // stage 6.
+};
+// pps end.
+
+struct series_t {
+ pte_t orig_ptes[MAX_SERIES_LENGTH];
+ pte_t* ptes[MAX_SERIES_LENGTH];
+ struct page* pages[MAX_SERIES_LENGTH];
+ int series_length;
+ int series_stage;
+} series;
+
+static int get_series_stage(pte_t* pte, int index)
+{
+ series.orig_ptes[index] = *pte;
+ series.ptes[index] = pte;
+ if (pte_present(series.orig_ptes[index])) {
+ struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
+ series.pages[index] = page;
+ if (page == ZERO_PAGE(addr)) // reserved page is exclusive from us.
+ return 7;
+ if (pte_young(series.orig_ptes[index])) {
+ return 1;
+ } else
+ return 2;
+ } else if (pte_unmapped(series.orig_ptes[index])) {
+ struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
+ series.pages[index] = page;
+ if (!PageSwapCache(page))
+ return 3;
+ else {
+ if (PageWriteback(page) || PageDirty(page))
+ return 4;
+ else
+ return 5;
+ }
+ } else // pte_swapped -- SwappedPTE
+ return 6;
+}
+
+static void find_series(pte_t** start, unsigned long* addr, unsigned long end)
+{
+ int i;
+ int series_stage = get_series_stage((*start)++, 0);
+ *addr += PAGE_SIZE;
+
+ for (i = 1; i < MAX_SERIES_LENGTH && *addr < end; i++, (*start)++,
+ *addr += PAGE_SIZE) {
+ if (series_stage != get_series_stage(*start, i))
+ break;
+ }
+ series.series_stage = series_stage;
+ series.series_length = i;
+}
+
+struct delay_tlb_task delay_tlb_tasks[32] = { [0 ... 31] = {0} };
+
+void timer_flush_tlb_tasks(void* data)
+{
+ int i;
+#ifdef CONFIG_X86
+ int flag = 0;
+#endif
+ for (i = 0; i < 32; i++) {
+ if (delay_tlb_tasks[i].mm != NULL &&
+ cpu_isset(smp_processor_id(),
+ delay_tlb_tasks[i].mm->cpu_vm_mask) &&
+ cpu_isset(smp_processor_id(),
+ delay_tlb_tasks[i].cpu_mask)) {
+#ifdef CONFIG_X86
+ flag = 1;
+#elif
+ // smp::local_flush_tlb_range(delay_tlb_tasks[i]);
+#endif
+ cpu_clear(smp_processor_id(), delay_tlb_tasks[i].cpu_mask);
+ }
+ }
+#ifdef CONFIG_X86
+ if (flag)
+ local_flush_tlb();
+#endif
+}
+
+static struct delay_tlb_task* delay_task = NULL;
+static int vma_index = 0;
+
+static struct delay_tlb_task* search_free_tlb_tasks_slot(void)
+{
+ struct delay_tlb_task* ret = NULL;
+ int i;
+again:
+ for (i = 0; i < 32; i++) {
+ if (delay_tlb_tasks[i].mm != NULL) {
+ if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
+ mmput(delay_tlb_tasks[i].mm);
+ delay_tlb_tasks[i].mm = NULL;
+ ret = &delay_tlb_tasks[i];
+ }
+ } else
+ ret = &delay_tlb_tasks[i];
+ }
+ if (!ret) { // Force flush TLBs.
+ on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
+ goto again;
+ }
+ return ret;
+}
+
+static void init_delay_task(struct mm_struct* mm)
+{
+ cpus_clear(delay_task->cpu_mask);
+ vma_index = 0;
+ delay_task->mm = mm;
+}
+
+/*
+ * We will be working on the mm, so let's force to flush it if necessary.
+ */
+static void start_tlb_tasks(struct mm_struct* mm)
+{
+ int i, flag = 0;
+again:
+ for (i = 0; i < 32; i++) {
+ if (delay_tlb_tasks[i].mm == mm) {
+ if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
+ mmput(delay_tlb_tasks[i].mm);
+ delay_tlb_tasks[i].mm = NULL;
+ } else
+ flag = 1;
+ }
+ }
+ if (flag) { // Force flush TLBs.
+ on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
+ goto again;
+ }
+ BUG_ON(delay_task != NULL);
+ delay_task = search_free_tlb_tasks_slot();
+ init_delay_task(mm);
+}
+
+static void end_tlb_tasks(void)
+{
+ atomic_inc(&delay_task->mm->mm_users);
+ delay_task->cpu_mask = delay_task->mm->cpu_vm_mask;
+ delay_task = NULL;
+#ifndef CONFIG_SMP
+ timer_flush_tlb_tasks(NULL);
+#endif
+}
+
+static void fill_in_tlb_tasks(struct vm_area_struct* vma, unsigned long addr,
+ unsigned long end)
+{
+ struct mm_struct* mm;
+ // First, try to combine the task with the previous.
+ if (vma_index != 0 && delay_task->vma[vma_index - 1] == vma &&
+ delay_task->end[vma_index - 1] == addr) {
+ delay_task->end[vma_index - 1] = end;
+ return;
+ }
+fill_it:
+ if (vma_index != 32) {
+ delay_task->vma[vma_index] = vma;
+ delay_task->start[vma_index] = addr;
+ delay_task->end[vma_index] = end;
+ vma_index++;
+ return;
+ }
+ mm = delay_task->mm;
+ end_tlb_tasks();
+
+ delay_task = search_free_tlb_tasks_slot();
+ init_delay_task(mm);
+ goto fill_it;
+}
+
+static void shrink_pvma_scan_ptes(struct scan_control* sc, struct mm_struct*
+ mm, struct vm_area_struct* vma, pmd_t* pmd, unsigned long addr,
+ unsigned long end)
+{
+ int i, statistic;
+ spinlock_t* ptl = pte_lockptr(mm, pmd);
+ pte_t* pte = pte_offset_map(pmd, addr);
+ int anon_rss = 0;
+ struct pagevec freed_pvec;
+ int may_enter_fs = (sc->gfp_mask & (__GFP_FS | __GFP_IO));
+ struct address_space* mapping = &swapper_space;
+
+ pagevec_init(&freed_pvec, 1);
+ do {
+ memset(&series, 0, sizeof(struct series_t));
+ find_series(&pte, &addr, end);
+ if (sc->may_reclaim == 0 && series.series_stage == 5)
+ continue;
+ switch (series.series_stage) {
+ case 1: // PTE -- untouched PTE.
+ for (i = 0; i < series.series_length; i++) {
+ struct page* page = series.pages[i];
+ lock_page(page);
+ spin_lock(ptl);
+ if (unlikely(pte_same(*series.ptes[i],
+ series.orig_ptes[i]))) {
+ if (pte_dirty(*series.ptes[i]))
+ set_page_dirty(page);
+ set_pte_at(mm, addr + i * PAGE_SIZE,
+ series.ptes[i],
+ pte_mkold(pte_mkclean(*series.ptes[i])));
+ }
+ spin_unlock(ptl);
+ unlock_page(page);
+ }
+ fill_in_tlb_tasks(vma, addr, addr + (PAGE_SIZE *
+ series.series_length));
+ break;
+ case 2: // untouched PTE -- UnmappedPTE.
+ /*
+ * Note in stage 1, we've flushed TLB in fill_in_tlb_tasks, so
+ * if it's still clear here, we can shift it to Unmapped type.
+ *
+ * If some architecture doesn't support atomic cmpxchg
+ * instruction or can't atomically set the access bit after
+ * they touch a pte at first, combine stage 1 with stage 2, and
+ * send IPI immediately in fill_in_tlb_tasks.
+ */
+ spin_lock(ptl);
+ statistic = 0;
+ for (i = 0; i < series.series_length; i++) {
+ if (unlikely(pte_same(*series.ptes[i],
+ series.orig_ptes[i]))) {
+ pte_t pte_unmapped = series.orig_ptes[i];
+ pte_unmapped.pte_low &= ~_PAGE_PRESENT;
+ pte_unmapped.pte_low |= _PAGE_UNMAPPED;
+ if (cmpxchg(&series.ptes[i]->pte_low,
+ series.orig_ptes[i].pte_low,
+ pte_unmapped.pte_low) !=
+ series.orig_ptes[i].pte_low)
+ continue;
+ page_remove_rmap(series.pages[i], vma);
+ anon_rss--;
+ statistic++;
+ }
+ }
+ atomic_add(statistic, &pps_info.unmapped_count);
+ atomic_sub(statistic, &pps_info.pte_count);
+ spin_unlock(ptl);
+ break;
+ case 3: // Attach SwapPage to PrivatePage.
+ /*
+ * A better arithmetic should be applied to Linux SwapDevice to
+ * allocate fake continual SwapPages which are close to each
+ * other, the offset between two close SwapPages is less than 8.
+ */
+ if (sc->may_swap) {
+ for (i = 0; i < series.series_length; i++) {
+ lock_page(series.pages[i]);
+ if (!PageSwapCache(series.pages[i])) {
+ if (!add_to_swap(series.pages[i],
+ GFP_ATOMIC)) {
+ unlock_page(series.pages[i]);
+ break;
+ }
+ }
+ unlock_page(series.pages[i]);
+ }
+ }
+ break;
+ case 4: // SwapPage isn't consistent with PrivatePage.
+ /*
+ * A mini version pageout().
+ *
+ * Current swap space can't commit multiple pages together:(
+ */
+ if (sc->may_writepage && may_enter_fs) {
+ for (i = 0; i < series.series_length; i++) {
+ struct page* page = series.pages[i];
+ int res;
+
+ if (!may_write_to_queue(mapping->backing_dev_info))
+ break;
+ lock_page(page);
+ if (!PageDirty(page) || PageWriteback(page)) {
+ unlock_page(page);
+ continue;
+ }
+ clear_page_dirty_for_io(page);
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = SWAP_CLUSTER_MAX,
+ .nonblocking = 1,
+ .for_reclaim = 1,
+ };
+ page_cache_get(page);
+ SetPageReclaim(page);
+ res = swap_writepage(page, &wbc);
+ if (res < 0) {
+ handle_write_error(mapping, page, res);
+ ClearPageReclaim(page);
+ page_cache_release(page);
+ break;
+ }
+ if (!PageWriteback(page))
+ ClearPageReclaim(page);
+ page_cache_release(page);
+ }
+ }
+ break;
+ case 5: // UnmappedPTE -- SwappedPTE, reclaim PrivatePage.
+ statistic = 0;
+ for (i = 0; i < series.series_length; i++) {
+ struct page* page = series.pages[i];
+ if (!(page_to_nid(page) == sc->reclaim_node ||
+ sc->reclaim_node == -1))
+ continue;
+
+ lock_page(page);
+ spin_lock(ptl);
+ if (!pte_same(*series.ptes[i], series.orig_ptes[i]) ||
+ /* We're racing with get_user_pages. */
+ PageSwapCache(page) ? page_count(page)
+ > 2 : page_count(page) > 1) {
+ spin_unlock(ptl);
+ unlock_page(page);
+ continue;
+ }
+ statistic++;
+ swp_entry_t entry = { .val = page_private(page) };
+ swap_duplicate(entry);
+ pte_t pte_swp = swp_entry_to_pte(entry);
+ set_pte_at(mm, addr + i * PAGE_SIZE,
+ series.ptes[i], pte_swp);
+ spin_unlock(ptl);
+ if (PageSwapCache(page) && !PageWriteback(page))
+ delete_from_swap_cache(page);
+ unlock_page(page);
+
+ if (!pagevec_add(&freed_pvec, page))
+ __pagevec_release_nonlru(&freed_pvec);
+ }
+ atomic_add(statistic, &pps_info.swapped_count);
+ atomic_sub(statistic, &pps_info.unmapped_count);
+ atomic_sub(statistic, &pps_info.total);
+ break;
+ case 6:
+ // NULL operation!
+ break;
+ }
+ } while (addr < end);
+ add_mm_counter(mm, anon_rss, anon_rss);
+ if (pagevec_count(&freed_pvec))
+ __pagevec_release_nonlru(&freed_pvec);
+}
+
+static void shrink_pvma_pmd_range(struct scan_control* sc, struct mm_struct*
+ mm, struct vm_area_struct* vma, pud_t* pud, unsigned long addr,
+ unsigned long end)
+{
+ unsigned long next;
+ pmd_t* pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ shrink_pvma_scan_ptes(sc, mm, vma, pmd, addr, next);
+ } while (pmd++, addr = next, addr != end);
+}
+
+static void shrink_pvma_pud_range(struct scan_control* sc, struct mm_struct*
+ mm, struct vm_area_struct* vma, pgd_t* pgd, unsigned long addr,
+ unsigned long end)
+{
+ unsigned long next;
+ pud_t* pud = pud_offset(pgd, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ shrink_pvma_pmd_range(sc, mm, vma, pud, addr, next);
+ } while (pud++, addr = next, addr != end);
+}
+
+static void shrink_pvma_pgd_range(struct scan_control* sc, struct mm_struct*
+ mm, struct vm_area_struct* vma)
+{
+ unsigned long next;
+ unsigned long addr = vma->vm_start;
+ unsigned long end = vma->vm_end;
+ pgd_t* pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ shrink_pvma_pud_range(sc, mm, vma, pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}
+
+static void shrink_private_vma(struct scan_control* sc)
+{
+ struct vm_area_struct* vma;
+ struct list_head *pos;
+ struct mm_struct *prev, *mm;
+
+ prev = mm = &init_mm;
+ pos = &init_mm.mmlist;
+ atomic_inc(&prev->mm_users);
+ spin_lock(&mmlist_lock);
+ while ((pos = pos->next) != &init_mm.mmlist) {
+ mm = list_entry(pos, struct mm_struct, mmlist);
+ if (!atomic_inc_not_zero(&mm->mm_users))
+ continue;
+ spin_unlock(&mmlist_lock);
+ mmput(prev);
+ prev = mm;
+ start_tlb_tasks(mm);
+ if (down_read_trylock(&mm->mmap_sem)) {
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ if (!(vma->vm_flags & VM_PURE_PRIVATE))
+ continue;
+ if (vma->vm_flags & VM_LOCKED)
+ continue;
+ shrink_pvma_pgd_range(sc, mm, vma);
+ }
+ up_read(&mm->mmap_sem);
+ }
+ end_tlb_tasks();
+ spin_lock(&mmlist_lock);
+ }
+ spin_unlock(&mmlist_lock);
+ mmput(prev);
+}
+
/*
* For kswapd, balance_pgdat() will work across all this node's zones until
* they are all at pages_high.
@@ -1144,6 +1585,11 @@
sc.may_writepage = !laptop_mode;
count_vm_event(PAGEOUTRUN);
+ wakeup_sc = sc;
+ wakeup_sc.may_reclaim = 1;
+ wakeup_sc.reclaim_node = pgdat->node_id;
+ wake_up_interruptible(&kppsd_wait);
+
for (i = 0; i < pgdat->nr_zones; i++)
temp_priority[i] = DEF_PRIORITY;
@@ -1723,3 +2169,39 @@
return __zone_reclaim(zone, gfp_mask, order);
}
#endif
+
+static int kppsd(void* p)
+{
+ struct task_struct *tsk = current;
+ int timeout;
+ DEFINE_WAIT(wait);
+ tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE;
+ struct scan_control default_sc;
+ default_sc.gfp_mask = GFP_KERNEL;
+ default_sc.may_writepage = 1;
+ default_sc.may_swap = 1;
+ default_sc.may_reclaim = 0;
+ default_sc.reclaim_node = -1;
+
+ while (1) {
+ try_to_freeze();
+ prepare_to_wait(&kppsd_wait, &wait, TASK_INTERRUPTIBLE);
+ timeout = schedule_timeout(2000);
+ finish_wait(&kppsd_wait, &wait);
+
+ if (timeout)
+ shrink_private_vma(&wakeup_sc);
+ else
+ shrink_private_vma(&default_sc);
+ }
+ return 0;
+}
+
+static int __init kppsd_init(void)
+{
+ init_waitqueue_head(&kppsd_wait);
+ kthread_run(kppsd, NULL, "kppsd");
+ return 0;
+}
+
+module_init(kppsd_init)
-
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