The patch titled writeback: the kupdate expire timestamp should be a moving target has been added to the -mm tree. Its filename is writeback-the-kupdate-expire-timestamp-should-be-a-moving-target.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: writeback: the kupdate expire timestamp should be a moving target From: Wu Fengguang <fengguang.wu@xxxxxxxxx> Dynamically compute the dirty expire timestamp at queue_io() time. writeback_control.older_than_this used to be determined at entrance to the kupdate writeback work. This _static_ timestamp may go stale if the kupdate work runs on and on. The flusher may then stuck with some old busy inodes, never considering newly expired inodes thereafter. This has two possible problems: - It is unfair for a large dirty inode to delay (for a long time) the writeback of small dirty inodes. - As time goes by, the large and busy dirty inode may contain only _freshly_ dirtied pages. Ignoring newly expired dirty inodes risks delaying the expired dirty pages to the end of LRU lists, triggering the evil pageout(). Nevertheless this patch merely addresses part of the problem. v2: keep policy changes inside wb_writeback() and keep the wbc.older_than_this visibility as suggested by Dave. Signed-off-by: Itaru Kitayama <kitayama@xxxxxxxxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Acked-by: Jan Kara <jack@xxxxxxx> Acked-by: Mel Gorman <mel@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/fs-writeback.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff -puN fs/fs-writeback.c~writeback-the-kupdate-expire-timestamp-should-be-a-moving-target fs/fs-writeback.c --- a/fs/fs-writeback.c~writeback-the-kupdate-expire-timestamp-should-be-a-moving-target +++ a/fs/fs-writeback.c @@ -661,11 +661,6 @@ static long wb_writeback(struct bdi_writ long write_chunk; struct inode *inode; - if (wbc.for_kupdate) { - wbc.older_than_this = &oldest_jif; - oldest_jif = jiffies - - msecs_to_jiffies(dirty_expire_interval * 10); - } if (!wbc.range_cyclic) { wbc.range_start = 0; wbc.range_end = LLONG_MAX; @@ -714,6 +709,12 @@ static long wb_writeback(struct bdi_writ if (work->for_background && !over_bground_thresh()) break; + if (work->for_kupdate) { + oldest_jif = jiffies - + msecs_to_jiffies(dirty_expire_interval * 10); + wbc.older_than_this = &oldest_jif; + } + wbc.more_io = 0; wbc.nr_to_write = write_chunk; wbc.pages_skipped = 0; _ Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are mm-per-node-vmstat-show-proper-vmstats.patch mm-per-node-vmstat-show-proper-vmstats-fix.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 -- 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