The patch titled
readahead: return early when readahead is disabled
has been removed from the -mm tree. Its filename was
readahead-return-early-when-readahead-is-disabled.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: readahead: return early when readahead is disabled
From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Reduce readahead overheads by returning early in do_sync_mmap_readahead().
tmpfs has ra_pages=0 and it can page fault really fast (not constraint by
IO if not swapping).
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Tested-by: Tim Chen <tim.c.chen@xxxxxxxxx>
Reported-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff -puN mm/filemap.c~readahead-return-early-when-readahead-is-disabled mm/filemap.c
--- a/mm/filemap.c~readahead-return-early-when-readahead-is-disabled
+++ a/mm/filemap.c
@@ -1556,6 +1556,8 @@ static void do_sync_mmap_readahead(struc
/* If we don't want any read-ahead, don't bother */
if (VM_RandomReadHint(vma))
return;
+ if (!ra->ra_pages)
+ return;
if (VM_SequentialReadHint(vma) ||
offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) {
@@ -1578,12 +1580,10 @@ static void do_sync_mmap_readahead(struc
* mmap read-around
*/
ra_pages = max_sane_readahead(ra->ra_pages);
- if (ra_pages) {
- ra->start = max_t(long, 0, offset - ra_pages/2);
- ra->size = ra_pages;
- ra->async_size = 0;
- ra_submit(ra, mapping, file);
- }
+ ra->start = max_t(long, 0, offset - ra_pages / 2);
+ ra->size = ra_pages;
+ ra->async_size = 0;
+ ra_submit(ra, mapping, file);
}
/*
_
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
origin.patch
writeback-pass-writeback_control-down-to-move_expired_inodes.patch
writeback-introduce-writeback_controlinodes_cleaned.patch
writeback-try-more-writeback-as-long-as-something-was-written.patch
writeback-the-kupdate-expire-timestamp-should-be-a-moving-target.patch
writeback-sync-expired-inodes-first-in-background-writeback.patch
writeback-sync-expired-inodes-first-in-background-writeback-fix.patch
writeback-refill-b_io-iff-empty.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix-fix.patch
writeback-elevate-queue_io-into-wb_writeback.patch
writeback-introduce-wbctagged_sync-for-the-wb_sync_none-sync-stage.patch
writeback-update-dirtied_when-for-synced-inode-to-prevent-livelock.patch
writeback-avoid-extra-sync-work-at-enqueue-time.patch
getdelays-show-average-cpu-io-swap-reclaim-delays.patch
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