Thanks for the reply. What version did this go into? I'll try getting a prebuilt backport of the kernel, building source could slow things down considerably, but debs will not be available for the latest few minor versions I guess. So if you can tell me a min version, I'll try to find the latest deb newer than that, or I'll build if that's not available.
On Mon, Oct 26, 2015 at 3:25 PM, Liu Bo <bo.li....@oracle.com> wrote: > On 10/26/2015 08:16 PM, cheater00 . wrote: >> >> Hi guys, >> I am running into really bad performance. Here's my setup: >> >> WD Red 6 TB connected over USB2 to my core i7 laptop, running Ubuntu >> 32-bit with kernel 4.0.4-040004-generic #201505171336. >> >> Single btrfs partition covering whole disk. >> >> Autodefrag is on. >> >> fstab line: >> UUID=... /media/X btrfs rw,nosuid,nodev,autodefrag 0 0 >> >> Sometimes when files are being modified or removed, I see >> btrfs-transacti eat 100% cpu; during this time no io operations >> succeed, that is, they're all stalled. You can't even ls on that fs. >> This happens for several minutes then normal operation resumes. There >> doesn't seem to be a rule to what will trigger this, other than >> opening a single file and reading usually works quite well. (say, >> watching a movie while all other programs are closed). But even moving >> files off the disks triggers some sort of bug. Just now I am moving a >> few files (just 30gb worth) onto another disk, and the bug triggers. >> So btrfs-transacti was eating my cpu for over 5 minutes and according >> to mv's output after this was done and cpu usage went back to normal >> what I was waiting for was for a tiny png file to be removed. This is >> pretty bad. >> >> I have tried defragmenting directories where files are being accessed >> and moved. This hasn't helped. >> >> This happens whether the FS is near full or not. It currently is near >> full but it wasn't before and it still did that. It still has about ~ >> 100GB free space now. >> >> The more things are happening the more often this bug gets triggered. >> So if I have utorrent running and its temporary downloads directory is >> there, its download speed graph will be a few spikes of running at >> several MB/sec separated by durations of 0 download speed. >> >> Nothing seems to show up in dmesg or syslog. >> >> I have asked in #btrfs but the suggestions ended up not fixing the >> issue (autodefrag, defrag dirs). >> >> Please advise what I should do with this issue. > > > It might be related to delayed ref rework, the last time I saw this kind of > hanging problem about btrfs-transaction eating cpu is that because btrfs > doesn't merge delayed refs, it'd be best to try the lastest kernel and if > the issue is not resolved, then we can work out a reproducer and provide > debugging. > > Thanks, > > Liubo -- 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
