From: Michael Rubin <[EMAIL PROTECTED]> Fixing a bug where writing to large files while concurrently writing to smaller ones creates a situation where writeback cannot keep up with the traffic and memory baloons until the we hit the threshold watermark. This can result in surprising latency spikes when syncing. This latency can take minutes on large memory systems. Upon request I can provide a test to reproduce this situation.
The only concern I have is that this makes the wb_kupdate slightly more agressive. I am not sure it is enough to cause any problems. I think there is enough checks to throttle the background activity. Feng also the one line change that you recommended here http://marc.info/?l=linux-kernel&m=119629655402153&w=2 had no effect. Signed-off-by: Michael Rubin <[EMAIL PROTECTED]> --- Index: 2624rc3_feng/fs/fs-writeback.c =================================================================== --- 2624rc3_feng.orig/fs/fs-writeback.c 2007-11-29 14:44:24.000000000 -0800 +++ 2624rc3_feng/fs/fs-writeback.c 2007-12-10 17:21:45.000000000 -0800 @@ -408,8 +408,7 @@ sync_sb_inodes(struct super_block *sb, s { const unsigned long start = jiffies; /* livelock avoidance */ - if (!wbc->for_kupdate || list_empty(&sb->s_io)) - queue_io(sb, wbc->older_than_this); + queue_io(sb, wbc->older_than_this); while (!list_empty(&sb->s_io)) { struct inode *inode = list_entry(sb->s_io.prev, Index: 2624rc3_feng/mm/page-writeback.c =================================================================== --- 2624rc3_feng.orig/mm/page-writeback.c 2007-11-16 21:16:36.000000000 -0800 +++ 2624rc3_feng/mm/page-writeback.c 2007-12-10 17:37:17.000000000 -0800 @@ -638,7 +638,7 @@ static void wb_kupdate(unsigned long arg wbc.nr_to_write = MAX_WRITEBACK_PAGES; writeback_inodes(&wbc); if (wbc.nr_to_write > 0) { - if (wbc.encountered_congestion || wbc.more_io) + if (wbc.encountered_congestion) congestion_wait(WRITE, HZ/10); else break; /* All the old data is written */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
