On 06/22/2011 10:15 AM, Henning Rohlfs wrote: > On Tue, 21 Jun 2011 11:24:11 -0400, Calvin Walton wrote: >> 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. > > You are right. This seems to be a regression in the .39 kernel. I tested > with 2.6.38.2 just now and the performance is back to normal.
Would you mind bisecting? You can make it go faster by doing git bisect start fs/ that way only changes in fs are used. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
