On Thu, 10 Nov 2011 10:06:16 +0000 Mel Gorman <mgorman@xxxxxxx> wrote: > Occasionally during large file copies to slow storage, there are still > reports of user-visible stalls when THP is enabled. Reports on this > have been intermittent and not reliable to reproduce locally but; If you want to cause a massive stall take a cheap 32GB USB flash drive plug it into an 8GB box and rsync a lot of small files to it. 400,000 emails in maildir format does the trick and can easily be simulated. The drive drops to about 1-2 IOPS with all the small mucking around and the backlog becomes massive. > Internally in SUSE, I received a bug report related to stalls in firefox > when using Java and Flash heavily while copying from NFS > to VFAT on USB. It has not been confirmed to be the same problem > but if it looks like a duck and quacks like a duck..... With the 32GB USB flash rsync I see firefox block for up to 45 minutes although operating entirely on an unrelated filesystem. I suspect it may be a problem that is visible because an fsync is getting jammed up in the mess. Alan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>