Messages in this thread Patch in this message | | | Date | Tue, 18 Aug 2009 16:55:23 +0100 | From | "Jan Beulich" <> | 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@novell.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-rc6/include/linux/bootmem.h 2009-06-10 05:05:27.000000000 +0200 +++ 2.6.31-rc6-alloc-small-hash/include/linux/bootmem.h 2009-08-17 15:21:17.000000000 +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-rc6/kernel/pid.c 2009-08-18 15:31:56.000000000 +0200 +++ 2.6.31-rc6-alloc-small-hash/kernel/pid.c 2009-08-17 15:21:17.000000000 +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-rc6/mm/page_alloc.c 2009-08-18 15:31:56.000000000 +0200 +++ 2.6.31-rc6-alloc-small-hash/mm/page_alloc.c 2009-08-17 15:21:17.000000000 +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 @@ -4728,7 +4728,14 @@ 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);
| |