The patch titled
swap-token: try to grab swap token before the VM selects pages for eviction
has been added to the -mm tree. Its filename is
swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: swap-token: try to grab swap token before the VM selects pages for eviction
From: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxxxx>
In the current implementation of swap token tuning, grab swap token is made
from:
1) after page_cache_read (filemap.c) and
2) after the readahead logic in do_swap_page (memory.c)
IMO, the contention for the swap token should happen _before_ the
aforementioned calls, because in the event of low system memory, calls to
freeup space will be made later from page_cache_read and read_swap_cache_async
, so we want to avoid "false LRU" pages by grabbing the token before the VM
starts searching for replacement candidates.
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/filemap.c | 2 +-
mm/memory.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff -puN mm/filemap.c~swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction mm/filemap.c
--- a/mm/filemap.c~swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction
+++ a/mm/filemap.c
@@ -1456,8 +1456,8 @@ no_cached_page:
* We're only likely to ever get here if MADV_RANDOM is in
* effect.
*/
+ grab_swap_token(); /* Contend for token _before_ we read-in */
error = page_cache_read(file, pgoff);
- grab_swap_token();
/*
* The page we want has now been added to the page cache.
diff -puN mm/memory.c~swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction mm/memory.c
--- a/mm/memory.c~swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction
+++ a/mm/memory.c
@@ -1989,6 +1989,7 @@ static int do_swap_page(struct mm_struct
delayacct_set_flag(DELAYACCT_PF_SWAPIN);
page = lookup_swap_cache(entry);
if (!page) {
+ grab_swap_token(); /* Contend for token _before_ we read-in */
swapin_readahead(entry, address, vma);
page = read_swap_cache_async(entry, vma, address);
if (!page) {
@@ -2006,7 +2007,6 @@ static int do_swap_page(struct mm_struct
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
- grab_swap_token();
}
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
_
Patches currently in -mm which might be from ashwin.chaugule@xxxxxxxxxxxx are
swap-token-try-to-grab-swap-token-before-the-vm-selects-pages-for-eviction.patch
swap-token-new-scheme-to-preempt-token.patch
swap-token-new-scheme-to-preempt-token-tidy.patch
-
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