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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html