diff options
author | Hideo AOKI | 2006-04-10 22:52:59 -0700 |
---|---|---|
committer | Linus Torvalds | 2006-04-11 06:18:32 -0700 |
commit | cb45b0e966cbe747b6189c15b108901cc7d6c97c (patch) | |
tree | 0402d4809ec175e80b083f7a713ec32c0109baad /include | |
parent | e23ca00bf1b1c6c0f04702cb4d29e275ab8dc330 (diff) |
[PATCH] overcommit: add calculate_totalreserve_pages()
These patches are an enhancement of OVERCOMMIT_GUESS algorithm in
__vm_enough_memory().
- why the kernel needed patching
When the kernel can't allocate anonymous pages in practice, currnet
OVERCOMMIT_GUESS could return success. This implementation might be
the cause of oom kill in memory pressure situation.
If the Linux runs with page reservation features like
/proc/sys/vm/lowmem_reserve_ratio and without swap region, I think
the oom kill occurs easily.
- the overall design approach in the patch
When the OVERCOMMET_GUESS algorithm calculates number of free pages,
the reserved free pages are regarded as non-free pages.
This change helps to avoid the pitfall that the number of free pages
become less than the number which the kernel tries to keep free.
- testing results
I tested the patches using my test kernel module.
If the patches aren't applied to the kernel, __vm_enough_memory()
returns success in the situation but autual page allocation is
failed.
On the other hand, if the patches are applied to the kernel, memory
allocation failure is avoided since __vm_enough_memory() returns
failure in the situation.
I checked that on i386 SMP 16GB memory machine. I haven't tested on
nommu environment currently.
This patch adds totalreserve_pages for __vm_enough_memory().
Calculate_totalreserve_pages() checks maximum lowmem_reserve pages and
pages_high in each zone. Finally, the function stores the sum of each
zone to totalreserve_pages.
The totalreserve_pages is calculated when the VM is initilized.
And the variable is updated when /proc/sys/vm/lowmem_reserve_raito
or /proc/sys/vm/min_free_kbytes are changed.
Signed-off-by: Hideo Aoki <haoki@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/swap.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index 54eac8a39a4c..5b1fdf1cff4f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -155,6 +155,7 @@ extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct * /* linux/mm/page_alloc.c */ extern unsigned long totalram_pages; extern unsigned long totalhigh_pages; +extern unsigned long totalreserve_pages; extern long nr_swap_pages; extern unsigned int nr_free_pages(void); extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat); |