Applications using fsync cause hangs for several seconds every few minutes
Hello,
Quoted 10 lines · Nirbheek Chauhan <nirbheek <at> gentoo.org> writes:
However, recently, perhaps with 2.6.39, or after I quickly started filling up my disk again, it has become impossible for me to work for long periods on my machine.
Every few minutes, (I guess) when applications do fsync (firefox, xchat, vim, etc), all applications that use
fsync()hang for several seconds, and applications that use general IO suffer extreme slowdowns. iotop shows various combinations of the processes listed below doing writes, and the total write as 2-3MB/s.
Quoted 5 lines
[btrfs-dealloc-]
[btrfs-submit-0]
[btrfs-transacti]
[btrfs-endio-wri]
[flush-btrfs-1]
I'm using btrfs under a 2.6.39-ARCH kernel and run into the same issue.
In my case the [btrfs-submit-0] and [btrfs-transacti] shows up in iotop and produce 99% of IO at the time a application is frozen. For something like 10 to 30 seconds.
After a fresh boot everything runs quiet acceptable and goes worse over the day. If I reboot the unmount process takes a lot of time something up to 8 minutes. After the reboot everything is back to normal. At least for a while.
I use snapshots on a daily base and have 20 active snapshots all the time. Maybe this is the reason for the performance impact?
Quoted 3 lines
What can I do to debug this issue? What other information should I supply? Could someone guide me on how to figure out why my machine is unusable now?
I have no solution for this problem. In fact a reboot helps me even if only temporary. I also changed the IO scheduler, switched to laptop mode and remounted the device. Neither of these helped.
Maybe someone else has any suggestion?
Thanks.
Jan Stilow