On Tue, Nov 02, 2010 at 07:47:15AM -0400, Sanjoy Mahajan wrote: > Chris Mason <chris.mason@xxxxxxxxxx> wrote: > > > > This has the appearance of some really bad IO or VM latency > > > problem. Unfixed and present in stable kernel versions going from > > > years ago all the way to v2.6.36. > > > > Hmmm, the workload you're describing here has two special parts. > > First it dramatically overloads the disk, and then it has guis doing > > things waiting for the disk. > > I think I see this same issue every few days when I back up my hard > drive to a USB hard drive using rsync. While the backup is running, the > interactive response is bad. A reproducible measurement of the badness > is starting an rxvt with F8 (bound to "rxvt &" in my .twmrc). Often it > takes 8 seconds for the window to appear (as it just did about 2 minutes > ago)! (Starting a subsequent rxvt is quick.) So this sounds like the backup is just thrashing your cache. Latencies starting an app are less surprising than latencies where a running app doesn't respond at all. Does rsync have the option to do an fadvise DONTNEED? -chris -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>