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Date: Mon, 11 Mar 2013 07:32:41 -0500
From: Cliff Wickman <cpw@....com>
To: Hillf Danton <dhillf@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
wli@...omorphy.com
Subject: Re: [PATCH] mm, x86: no zeroing of hugetlbfs pages at boot
On Sun, Mar 10, 2013 at 01:55:10PM +0800, Hillf Danton wrote:
> On Thu, Mar 7, 2013 at 5:50 AM, Cliff Wickman <cpw@....com> wrote:
> > From: Cliff Wickman <cpw@....com>
> >
> > Allocating a large number of 1GB hugetlbfs pages at boot takes a
> > very long time.
> >
> > Large system sites would at times like to allocate a very large amount of
> > memory as 1GB pages. They would put this on the kernel boot line:
> > default_hugepagesz=1G hugepagesz=1G hugepages=4096
> > [Dynamic allocation of 1G pages is not an option, as zone pages only go
> > up to MAX_ORDER, and MAX_ORDER cannot exceed the section size.]
> >
> > Each page is zeroed as it is allocated, and all allocation is done by
> > cpu 0, as this path is early in boot:
> > start_kernel
> > kernel_init
> > do_pre_smp_initcalls
> > hugetlb_init
> > hugetlb_init_hstates
> > hugetlb_hstate_alloc_pages
> >
> > Zeroing remote (offnode) memory takes ~1GB/sec (and most memory is offnode
> > on large numa systems).
> > This estimate is approximate (it depends on core frequency & number of hops
> > to remote memory) but should be within a factor of 2 on most systems.
> > A benchmark attempting to reserve a TB for 1GB pages would thus require
> > ~1000 seconds of boot time just for this allocating. 32TB would take 8 hours.
> >
> > I propose passing a flag to the early allocator to indicate that no zeroing
> > of a page should be done. The 'no zeroing' flag would have to be passed
> > down this code path:
> >
>
> FYI: huge pages are cleared just after allocated, for instance,
> clear_huge_page() in hugetlb_no_page()
>
> Hillf
Yes, I should have added that comment to the changelog. And because
this is true there is no need to clear a huge page at boot time.
-Cliff
> > hugetlb_hstate_alloc_pages
> > alloc_bootmem_huge_page
> > __alloc_bootmem_node_nopanic NO_ZERO (nobootmem.c)
> > __alloc_memory_core_early NO_ZERO
> > if (!(flags & NO_ZERO))
> > memset(ptr, 0, size);
> >
> > Or this path if CONFIG_NO_BOOTMEM is not set:
> >
> > hugetlb_hstate_alloc_pages
> > alloc_bootmem_huge_page
> > __alloc_bootmem_node_nopanic NO_ZERO (bootmem.c)
> > alloc_bootmem_core NO_ZERO
> > if (!(flags & NO_ZERO))
> > memset(region, 0, size);
> > __alloc_bootmem_nopanic NO_ZERO
> > ___alloc_bootmem_nopanic NO_ZERO
> > alloc_bootmem_core NO_ZERO
> > if (!(flags & NO_ZERO))
> > memset(region, 0, size);
> >
> > Signed-off-by: Cliff Wickman <cpw@....com>
> >
> > ---
> > arch/x86/kernel/setup_percpu.c | 4 ++--
> > include/linux/bootmem.h | 23 ++++++++++++++++-------
> > mm/bootmem.c | 12 +++++++-----
> > mm/hugetlb.c | 3 ++-
> > mm/nobootmem.c | 41 +++++++++++++++++++++++------------------
> > mm/page_cgroup.c | 2 +-
> > mm/sparse.c | 2 +-
> > 7 files changed, 52 insertions(+), 35 deletions(-)
> >
> > Index: linux/include/linux/bootmem.h
> > ===================================================================
> > --- linux.orig/include/linux/bootmem.h
> > +++ linux/include/linux/bootmem.h
> > @@ -8,6 +8,11 @@
> > #include <asm/dma.h>
> >
> > /*
> > + * allocation flags
> > + */
> > +#define NO_ZERO 0x00000001
> > +
> > +/*
> > * simple boot-time physical memory area allocator.
> > */
> >
> > @@ -79,7 +84,8 @@ extern void *__alloc_bootmem(unsigned lo
> > unsigned long goal);
> > extern void *__alloc_bootmem_nopanic(unsigned long size,
> > unsigned long align,
> > - unsigned long goal);
> > + unsigned long goal,
> > + u32 flags);
> > extern void *__alloc_bootmem_node(pg_data_t *pgdat,
> > unsigned long size,
> > unsigned long align,
> > @@ -91,12 +97,14 @@ void *__alloc_bootmem_node_high(pg_data_
> > extern void *__alloc_bootmem_node_nopanic(pg_data_t *pgdat,
> > unsigned long size,
> > unsigned long align,
> > - unsigned long goal);
> > + unsigned long goal,
> > + u32 flags);
> > void *___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
> > unsigned long size,
> > unsigned long align,
> > unsigned long goal,
> > - unsigned long limit);
> > + unsigned long limit,
> > + u32 flags);
> > extern void *__alloc_bootmem_low(unsigned long size,
> > unsigned long align,
> > unsigned long goal);
> > @@ -120,19 +128,20 @@ extern void *__alloc_bootmem_low_node(pg
> > #define alloc_bootmem_align(x, align) \
> > __alloc_bootmem(x, align, BOOTMEM_LOW_LIMIT)
> > #define alloc_bootmem_nopanic(x) \
> > - __alloc_bootmem_nopanic(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
> > + __alloc_bootmem_nopanic(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT, 0)
> > #define alloc_bootmem_pages(x) \
> > __alloc_bootmem(x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
> > #define alloc_bootmem_pages_nopanic(x) \
> > - __alloc_bootmem_nopanic(x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
> > + __alloc_bootmem_nopanic(x, PAGE_SIZE, BOOTMEM_LOW_LIMIT, 0)
> > #define alloc_bootmem_node(pgdat, x) \
> > __alloc_bootmem_node(pgdat, x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
> > #define alloc_bootmem_node_nopanic(pgdat, x) \
> > - __alloc_bootmem_node_nopanic(pgdat, x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
> > + __alloc_bootmem_node_nopanic(pgdat, x, SMP_CACHE_BYTES, \
> > + BOOTMEM_LOW_LIMIT, 0)
> > #define alloc_bootmem_pages_node(pgdat, x) \
> > __alloc_bootmem_node(pgdat, x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
> > #define alloc_bootmem_pages_node_nopanic(pgdat, x) \
> > - __alloc_bootmem_node_nopanic(pgdat, x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
> > + __alloc_bootmem_node_nopanic(pgdat, x, PAGE_SIZE, BOOTMEM_LOW_LIMIT, 0)
> >
> > #define alloc_bootmem_low(x) \
> > __alloc_bootmem_low(x, SMP_CACHE_BYTES, 0)
> > Index: linux/arch/x86/kernel/setup_percpu.c
> > ===================================================================
> > --- linux.orig/arch/x86/kernel/setup_percpu.c
> > +++ linux/arch/x86/kernel/setup_percpu.c
> > @@ -104,14 +104,14 @@ static void * __init pcpu_alloc_bootmem(
> > void *ptr;
> >
> > if (!node_online(node) || !NODE_DATA(node)) {
> > - ptr = __alloc_bootmem_nopanic(size, align, goal);
> > + ptr = __alloc_bootmem_nopanic(size, align, goal, 0);
> > pr_info("cpu %d has no node %d or node-local memory\n",
> > cpu, node);
> > pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
> > cpu, size, __pa(ptr));
> > } else {
> > ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
> > - size, align, goal);
> > + size, align, goal, 0);
> > pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
> > cpu, size, node, __pa(ptr));
> > }
> > Index: linux/mm/nobootmem.c
> > ===================================================================
> > --- linux.orig/mm/nobootmem.c
> > +++ linux/mm/nobootmem.c
> > @@ -33,7 +33,7 @@ unsigned long min_low_pfn;
> > unsigned long max_pfn;
> >
> > static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
> > - u64 goal, u64 limit)
> > + u64 goal, u64 limit, u32 flags)
> > {
> > void *ptr;
> > u64 addr;
> > @@ -46,7 +46,8 @@ static void * __init __alloc_memory_core
> > return NULL;
> >
> > ptr = phys_to_virt(addr);
> > - memset(ptr, 0, size);
> > + if (!(flags & NO_ZERO))
> > + memset(ptr, 0, size);
> > memblock_reserve(addr, size);
> > /*
> > * The min_count is set to 0 so that bootmem allocated blocks
> > @@ -208,7 +209,8 @@ void __init free_bootmem(unsigned long a
> > static void * __init ___alloc_bootmem_nopanic(unsigned long size,
> > unsigned long align,
> > unsigned long goal,
> > - unsigned long limit)
> > + unsigned long limit,
> > + u32 flags)
> > {
> > void *ptr;
> >
> > @@ -217,7 +219,8 @@ static void * __init ___alloc_bootmem_no
> >
> > restart:
> >
> > - ptr = __alloc_memory_core_early(MAX_NUMNODES, size, align, goal, limit);
> > + ptr = __alloc_memory_core_early(MAX_NUMNODES, size, align, goal,
> > + limit, 0);
> >
> > if (ptr)
> > return ptr;
> > @@ -244,17 +247,17 @@ restart:
> > * Returns NULL on failure.
> > */
> > void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
> > - unsigned long goal)
> > + unsigned long goal, u32 flags)
> > {
> > unsigned long limit = -1UL;
> >
> > - return ___alloc_bootmem_nopanic(size, align, goal, limit);
> > + return ___alloc_bootmem_nopanic(size, align, goal, limit, flags);
> > }
> >
> > static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
> > - unsigned long goal, unsigned long limit)
> > + unsigned long goal, unsigned long limit, u32 flags)
> > {
> > - void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit);
> > + void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit, flags);
> >
> > if (mem)
> > return mem;
> > @@ -284,25 +287,26 @@ void * __init __alloc_bootmem(unsigned l
> > {
> > unsigned long limit = -1UL;
> >
> > - return ___alloc_bootmem(size, align, goal, limit);
> > + return ___alloc_bootmem(size, align, goal, limit, 0);
> > }
> >
> > void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
> > unsigned long size,
> > unsigned long align,
> > unsigned long goal,
> > - unsigned long limit)
> > + unsigned long limit,
> > + u32 flags)
> > {
> > void *ptr;
> >
> > again:
> > ptr = __alloc_memory_core_early(pgdat->node_id, size, align,
> > - goal, limit);
> > + goal, limit, flags);
> > if (ptr)
> > return ptr;
> >
> > ptr = __alloc_memory_core_early(MAX_NUMNODES, size, align,
> > - goal, limit);
> > + goal, limit, flags);
> > if (ptr)
> > return ptr;
> >
> > @@ -315,12 +319,13 @@ again:
> > }
> >
> > void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
> > - unsigned long align, unsigned long goal)
> > + unsigned long align, unsigned long goal, u32 flags)
> > {
> > if (WARN_ON_ONCE(slab_is_available()))
> > return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
> >
> > - return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
> > + return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal,
> > + 0, flags);
> > }
> >
> > void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
> > @@ -329,7 +334,7 @@ void * __init ___alloc_bootmem_node(pg_d
> > {
> > void *ptr;
> >
> > - ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, limit);
> > + ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, limit, 0);
> > if (ptr)
> > return ptr;
> >
> > @@ -354,7 +359,7 @@ void * __init ___alloc_bootmem_node(pg_d
> > * The function panics if the request can not be satisfied.
> > */
> > void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
> > - unsigned long align, unsigned long goal)
> > + unsigned long align, unsigned long goal)
> > {
> > if (WARN_ON_ONCE(slab_is_available()))
> > return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
> > @@ -388,7 +393,7 @@ void * __init __alloc_bootmem_node_high(
> > void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
> > unsigned long goal)
> > {
> > - return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT);
> > + return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT, 0);
> > }
> >
> > void * __init __alloc_bootmem_low_nopanic(unsigned long size,
> > @@ -396,7 +401,7 @@ void * __init __alloc_bootmem_low_nopani
> > unsigned long goal)
> > {
> > return ___alloc_bootmem_nopanic(size, align, goal,
> > - ARCH_LOW_ADDRESS_LIMIT);
> > + ARCH_LOW_ADDRESS_LIMIT, 0);
> > }
> >
> > /**
> > Index: linux/mm/sparse.c
> > ===================================================================
> > --- linux.orig/mm/sparse.c
> > +++ linux/mm/sparse.c
> > @@ -281,7 +281,7 @@ sparse_early_usemaps_alloc_pgdat_section
> > nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
> > again:
> > p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
> > - SMP_CACHE_BYTES, goal, limit);
> > + SMP_CACHE_BYTES, goal, limit, 0);
> > if (!p && limit) {
> > limit = 0;
> > goto again;
> > Index: linux/mm/hugetlb.c
> > ===================================================================
> > --- linux.orig/mm/hugetlb.c
> > +++ linux/mm/hugetlb.c
> > @@ -1188,7 +1188,8 @@ int __weak alloc_bootmem_huge_page(struc
> > addr = __alloc_bootmem_node_nopanic(
> > NODE_DATA(hstate_next_node_to_alloc(h,
> > &node_states[N_MEMORY])),
> > - huge_page_size(h), huge_page_size(h), 0);
> > + huge_page_size(h), huge_page_size(h),
> > + 0, NO_ZERO);
> >
> > if (addr) {
> > /*
> > Index: linux/mm/bootmem.c
> > ===================================================================
> > --- linux.orig/mm/bootmem.c
> > +++ linux/mm/bootmem.c
> > @@ -660,7 +660,7 @@ restart:
> > * Returns NULL on failure.
> > */
> > void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
> > - unsigned long goal)
> > + unsigned long goal, u32 flags)
> > {
> > unsigned long limit = 0;
> >
> > @@ -705,7 +705,8 @@ void * __init __alloc_bootmem(unsigned l
> >
> > void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
> > unsigned long size, unsigned long align,
> > - unsigned long goal, unsigned long limit)
> > + unsigned long goal, unsigned long limit,
> > + u32 flags)
> > {
> > void *ptr;
> >
> > @@ -734,12 +735,13 @@ again:
> > }
> >
> > void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
> > - unsigned long align, unsigned long goal)
> > + unsigned long align, unsigned long goal, u32 flags)
> > {
> > if (WARN_ON_ONCE(slab_is_available()))
> > return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
> >
> > - return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
> > + return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal,
> > + 0, flags);
> > }
> >
> > void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
> > @@ -748,7 +750,7 @@ void * __init ___alloc_bootmem_node(pg_d
> > {
> > void *ptr;
> >
> > - ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
> > + ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0, 0);
> > if (ptr)
> > return ptr;
> >
> > Index: linux/mm/page_cgroup.c
> > ===================================================================
> > --- linux.orig/mm/page_cgroup.c
> > +++ linux/mm/page_cgroup.c
> > @@ -55,7 +55,7 @@ static int __init alloc_node_page_cgroup
> > table_size = sizeof(struct page_cgroup) * nr_pages;
> >
> > base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
> > - table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
> > + table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS), 0);
> > if (!base)
> > return -ENOMEM;
> > NODE_DATA(nid)->node_page_cgroup = base;
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
> >
> >
--
Cliff Wickman
SGI
cpw@....com
(651) 683-3824
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