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authorAndrew Morton <akpm@linux-foundation.org>2008-03-24 12:29:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-24 19:22:19 -0700
commit4dd4b920218326231156c7991ce5b94afad841c3 (patch)
tree021d883ec96cd67f5a348eb739a5c6596fcf6d04 /mm/vmscan.c
parenthw_random doc updates (diff)
downloadlinux-dev-4dd4b920218326231156c7991ce5b94afad841c3.tar.xz
linux-dev-4dd4b920218326231156c7991ce5b94afad841c3.zip
revert "kswapd should only wait on IO if there is IO"
Revert commit f1a9ee758de7de1e040de849fdef46e6802ea117: Author: Rik van Riel <riel@redhat.com> Date: Thu Feb 7 00:14:08 2008 -0800 kswapd should only wait on IO if there is IO The current kswapd (and try_to_free_pages) code has an oddity where the code will wait on IO, even if there is no IO in flight. This problem is notable especially when the system scans through many unfreeable pages, causing unnecessary stalls in the VM. Additionally, tasks without __GFP_FS or __GFP_IO in the direct reclaim path will sleep if a significant number of pages are encountered that should be written out. This gives kswapd a chance to write out those pages, while the direct reclaim task sleeps. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Because of large latencies and interactivity problems reported by Carlos, here: http://lkml.org/lkml/2008/3/22/211 Cc: Rik van Riel <riel@redhat.com> Cc: "Carlos R. Mafra" <crmafra2@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/vmscan.c27
1 files changed, 5 insertions, 22 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 45711585684e..4046434046e6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -70,13 +70,6 @@ struct scan_control {
int order;
- /*
- * Pages that have (or should have) IO pending. If we run into
- * a lot of these, we're better off waiting a little for IO to
- * finish rather than scanning more pages in the VM.
- */
- int nr_io_pages;
-
/* Which cgroup do we reclaim from */
struct mem_cgroup *mem_cgroup;
@@ -512,10 +505,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
*/
if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
wait_on_page_writeback(page);
- else {
- sc->nr_io_pages++;
+ else
goto keep_locked;
- }
}
referenced = page_referenced(page, 1, sc->mem_cgroup);
@@ -554,10 +545,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (PageDirty(page)) {
if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
goto keep_locked;
- if (!may_enter_fs) {
- sc->nr_io_pages++;
+ if (!may_enter_fs)
goto keep_locked;
- }
if (!sc->may_writepage)
goto keep_locked;
@@ -568,10 +557,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
case PAGE_ACTIVATE:
goto activate_locked;
case PAGE_SUCCESS:
- if (PageWriteback(page) || PageDirty(page)) {
- sc->nr_io_pages++;
+ if (PageWriteback(page) || PageDirty(page))
goto keep;
- }
/*
* A synchronous write - probably a ramdisk. Go
* ahead and try to reclaim the page.
@@ -1344,7 +1331,6 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
sc->nr_scanned = 0;
- sc->nr_io_pages = 0;
if (!priority)
disable_swap_token();
nr_reclaimed += shrink_zones(priority, zones, sc);
@@ -1379,8 +1365,7 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
}
/* Take a nap, wait for some writeback to complete */
- if (sc->nr_scanned && priority < DEF_PRIORITY - 2 &&
- sc->nr_io_pages > sc->swap_cluster_max)
+ if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
congestion_wait(WRITE, HZ/10);
}
/* top priority shrink_caches still had more to do? don't OOM, then */
@@ -1514,7 +1499,6 @@ loop_again:
if (!priority)
disable_swap_token();
- sc.nr_io_pages = 0;
all_zones_ok = 1;
/*
@@ -1607,8 +1591,7 @@ loop_again:
* OK, kswapd is getting into trouble. Take a nap, then take
* another pass across the zones.
*/
- if (total_scanned && priority < DEF_PRIORITY - 2 &&
- sc.nr_io_pages > sc.swap_cluster_max)
+ if (total_scanned && priority < DEF_PRIORITY - 2)
congestion_wait(WRITE, HZ/10);
/*