On Mon, 2011-06-20 at 23:51 +0200, Henning Rohlfs wrote: > Hello, > > I've migrated my system to btrfs (raid1) a few months ago. Since then > the performance has been pretty bad, but recently it's gotten > unbearable: a simple sync called while the system is idle can take 20 up > to 60 seconds. Creating or deleting files often has several seconds > latency, too. I think I’ve been seeing a fairly similar, or possibly the same? issue as well. It looks like it’s actually a regression introduced in 2.6.39 - if I switch back to a 2.6.38 kernel, my latency issues magically go away! (I'm curious: does using the older 2.6.38.x kernel help with anyone else that's seeing the issue?) Some hardware/configuration details: btrfs on a single disc (Seagate Momentus XT hybrid), lzo compression and space cache enabled. Some snapshots in use. I notice that in latencytop I'm seeing a lot of lines with (cropped) traces like sleep_on_page wait_on_page_bit read_extent_buffer_ 13.3 msec 0.5 % showing up that I didn't see with the 2.6.38 kernel. I occasionally see latencies as bad as 20-30 seconds on operations like fsync or synchronous writes. I think I can reproduce the issue well enough to bisect it, so I might give that a try. It'll be slow going, though. -- Calvin Walton <calvin.walton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
