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Date: Tue, 30 Jun 2009 12:12:19 +0100
From: "Jan Beulich" <JBeulich@...ell.com>
To: "Rusty Russell" <rusty@...tcorp.com.au>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH] also use alloc_large_system_hash() for the PID hash
table
This is being done by allowing boot time allocations to specify that
they may want a sub-page sized amount of memory.
Overall this seems more consistent with the other hash table
allocations, and allows making two supposedly mm-only variables really
mm-only (nr_{kernel,all}_pages).
Signed-off-by: Jan Beulich <jbeulich@...ell.com>
---
include/linux/bootmem.h | 5 ++---
kernel/pid.c | 15 ++++-----------
mm/page_alloc.c | 13 ++++++++++---
3 files changed, 16 insertions(+), 17 deletions(-)
--- linux-2.6.31-rc1/include/linux/bootmem.h 2009-06-10 05:05:27.000000000 +0200
+++ 2.6.31-rc1-alloc-small-hash/include/linux/bootmem.h 2009-06-25 13:21:59.000000000 +0200
@@ -132,9 +132,6 @@ static inline void *alloc_remap(int nid,
}
#endif /* CONFIG_HAVE_ARCH_ALLOC_REMAP */
-extern unsigned long __meminitdata nr_kernel_pages;
-extern unsigned long __meminitdata nr_all_pages;
-
extern void *alloc_large_system_hash(const char *tablename,
unsigned long bucketsize,
unsigned long numentries,
@@ -145,6 +142,8 @@ extern void *alloc_large_system_hash(con
unsigned long limit);
#define HASH_EARLY 0x00000001 /* Allocating during early boot? */
+#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min
+ * shift passed via *_hash_shift */
/* Only NUMA needs hash distribution. 64bit NUMA architectures have
* sufficient vmalloc space.
--- linux-2.6.31-rc1/kernel/pid.c 2009-06-26 17:50:00.000000000 +0200
+++ 2.6.31-rc1-alloc-small-hash/kernel/pid.c 2009-06-25 13:16:36.000000000 +0200
@@ -40,7 +40,7 @@
#define pid_hashfn(nr, ns) \
hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
static struct hlist_head *pid_hash;
-static int pidhash_shift;
+static unsigned int pidhash_shift = 4;
struct pid init_struct_pid = INIT_STRUCT_PID;
int pid_max = PID_MAX_DEFAULT;
@@ -499,19 +499,12 @@ struct pid *find_ge_pid(int nr, struct p
void __init pidhash_init(void)
{
int i, pidhash_size;
- unsigned long megabytes = nr_kernel_pages >> (20 - PAGE_SHIFT);
- pidhash_shift = max(4, fls(megabytes * 4));
- pidhash_shift = min(12, pidhash_shift);
+ pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
+ HASH_EARLY | HASH_SMALL,
+ &pidhash_shift, NULL, 4096);
pidhash_size = 1 << pidhash_shift;
- printk("PID hash table entries: %d (order: %d, %Zd bytes)\n",
- pidhash_size, pidhash_shift,
- pidhash_size * sizeof(struct hlist_head));
-
- pid_hash = alloc_bootmem(pidhash_size * sizeof(*(pid_hash)));
- if (!pid_hash)
- panic("Could not alloc pidhash!\n");
for (i = 0; i < pidhash_size; i++)
INIT_HLIST_HEAD(&pid_hash[i]);
}
--- linux-2.6.31-rc1/mm/page_alloc.c 2009-06-26 17:50:00.000000000 +0200
+++ 2.6.31-rc1-alloc-small-hash/mm/page_alloc.c 2009-06-26 16:11:36.000000000 +0200
@@ -123,8 +123,8 @@ static char * const zone_names[MAX_NR_ZO
int min_free_kbytes = 1024;
-unsigned long __meminitdata nr_kernel_pages;
-unsigned long __meminitdata nr_all_pages;
+static unsigned long __meminitdata nr_kernel_pages;
+static unsigned long __meminitdata nr_all_pages;
static unsigned long __meminitdata dma_reserve;
#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
@@ -4716,7 +4716,14 @@ void *__init alloc_large_system_hash(con
numentries <<= (PAGE_SHIFT - scale);
/* Make sure we've got at least a 0-order allocation.. */
- if (unlikely((numentries * bucketsize) < PAGE_SIZE))
+ if (unlikely(flags & HASH_SMALL)) {
+ /* Makes no sense without HASH_EARLY */
+ WARN_ON(!(flags & HASH_EARLY));
+ if (!(numentries >> *_hash_shift)) {
+ numentries = 1UL << *_hash_shift;
+ BUG_ON(!numentries);
+ }
+ } else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
numentries = PAGE_SIZE / bucketsize;
}
numentries = roundup_pow_of_two(numentries);
--
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