Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=fa1de9008c9bcce8ab5122529dd19b24c273eba2
Commit: fa1de9008c9bcce8ab5122529dd19b24c273eba2
Parent: 436c6541b13a73790646eb11429bdc8ee50eec41
Author: Hugh Dickins <[EMAIL PROTECTED]>
AuthorDate: Thu Feb 7 00:14:13 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Feb 7 08:42:20 2008 -0800
memcgroup: revert swap_state mods
If we're charging rss and we're charging cache, it seems obvious that we
should be charging swapcache - as has been done. But in practice that
doesn't work out so well: both swapin readahead and swapoff leave the
majority of pages charged to the wrong cgroup (the cgroup that happened to
read them in, rather than the cgroup to which they belong).
(Which is why unuse_pte's GFP_KERNEL while holding pte lock never showed up
as a problem: no allocation was ever done there, every page read being
already charged to the cgroup which initiated the swapoff.)
It all works rather better if we leave the charging to do_swap_page and
unuse_pte, and do nothing for swapcache itself: revert mm/swap_state.c to
what it was before the memory-controller patches. This also speeds up
significantly a contained process working at its limit: because it no
longer needs to keep waiting for swap writeback to complete.
Is it unfair that swap pages become uncharged once they're unmapped, even
though they're still clearly private to particular cgroups? For a short
while, yes; but PageReclaim arranges for those pages to go to the end of
the inactive list and be reclaimed soon if necessary.
shmem/tmpfs pages are a distinct case: their charging also benefits from
this change, but their second life on the lists as swapcache pages may
prove more unfair - that I need to check next.
Signed-off-by: Hugh Dickins <[EMAIL PROTECTED]>
Cc: Pavel Emelianov <[EMAIL PROTECTED]>
Acked-by: Balbir Singh <[EMAIL PROTECTED]>
Cc: Paul Menage <[EMAIL PROTECTED]>
Cc: Peter Zijlstra <[EMAIL PROTECTED]>
Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
Cc: Nick Piggin <[EMAIL PROTECTED]>
Cc: Kirill Korotaev <[EMAIL PROTECTED]>
Cc: Herbert Poetzl <[EMAIL PROTECTED]>
Cc: David Rientjes <[EMAIL PROTECTED]>
Cc: Vaidyanathan Srinivasan <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
mm/swap_state.c | 13 +------------
1 files changed, 1 insertions(+), 12 deletions(-)
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 6ce0669..ec42f01 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -17,7 +17,6 @@
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/migrate.h>
-#include <linux/memcontrol.h>
#include <asm/pgtable.h>
@@ -75,11 +74,6 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry,
gfp_t gfp_mask)
BUG_ON(!PageLocked(page));
BUG_ON(PageSwapCache(page));
BUG_ON(PagePrivate(page));
-
- error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
- if (error)
- goto out;
-
error = radix_tree_preload(gfp_mask);
if (!error) {
write_lock_irq(&swapper_space.tree_lock);
@@ -92,14 +86,10 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry,
gfp_t gfp_mask)
total_swapcache_pages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
INC_CACHE_INFO(add_total);
- } else {
- mem_cgroup_uncharge_page(page);
}
write_unlock_irq(&swapper_space.tree_lock);
radix_tree_preload_end();
- } else
- mem_cgroup_uncharge_page(page);
-out:
+ }
return error;
}
@@ -114,7 +104,6 @@ void __delete_from_swap_cache(struct page *page)
BUG_ON(PageWriteback(page));
BUG_ON(PagePrivate(page));
- mem_cgroup_uncharge_page(page);
radix_tree_delete(&swapper_space.page_tree, page_private(page));
set_page_private(page, 0);
ClearPageSwapCache(page);
-
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