On 08/18/2011 03:29 AM, Andrew Guertin wrote: > I have not seen slowdowns on 2.6.38. More specifically, I observe the > following behaviors after commit 4e69b59: > > * Many processes occasionally hang for a short time > * When this happens, my cpu monitor shows a short burst of cpu activity > (100% of 1 core) followed by a longer period of IO > * When this happens, iotop shows [btrfs-submit-0] and [btrfs-transacti] > at the top of the list > * Behavior slowly increases in duration (and frequency?) over time, and > goes away with a reboot > * Heavy IO makes behavior appear faster > > ... and the following behaviors before commit 4e69b59: > > * Occasional spikes of IO on cpu monitor concurrent with > [btrfs-submit-0] and [btrfs-transacti] at top of iotop > * No hangs, even when that occurs > > I wasn't taking notes or anything though, so I'm not 100% certain I was > observing or interpreting or remembering everything correctly.
I've investigated a little more, and have a few things to add: Before commit 4e69b59: * In the IO spikes where [btrfs-submit-0] and [btrfs-transacti] are at the top of iotop, there is no short burst of cpu activity preceding them * When running gentoo's emerge --sync (which IIRC is mainly an rsync of ~200MB of small files), output appears to pause during these spikes. I wasn't able to tell if output stopped entirely or just slowed down. --Andrew -- 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
