On Fri, Dec 09, 2011 at 12:05:40PM +0000, Jeremy Sanders wrote: > On 08/12/11 20:11, Chris Mason wrote: > >On Thu, Dec 08, 2011 at 05:39:16PM +0000, Jeremy Sanders wrote: > >>On 08/12/11 17:23, Chris Mason wrote: > >>>On Thu, Dec 08, 2011 at 04:57:12PM +0000, Jeremy Sanders wrote: > >>>>On 08/12/11 15:32, Chris Mason wrote: > >>>>>On Thu, Dec 08, 2011 at 03:19:38PM +0000, Jeremy Sanders wrote: > >>>>>>Hi - I'm trying out btrfs again, and I see the same old bug in kernel 3.1.4 > >>>>>>(Fedora 16, x86_64, dual-core), where after a few hours of writing, it > >>>>>>switches from writing with several threads to writing with one: > >>>>> > >>>>>Ok, I'll try to reproduce this here. Could you please do a sysrq-t, I'd > >>>>>like to see what the other delalloc-writers are doing. > >>>> > >>>>I've attached sysrq-t. It looks like it might be truncated at the > >>>>beginning, however. > >>> > >>>/var/log/messages may have the whole thing, please do check. > >> > >>That was from /var/log/messages. I think it needs a longer > >>log_buf_len. Unfortunately the system hasn't come back from its > >>reboot, so it will have to wait until tomorrow when I can get to it > >>physically. > > > >Ok, this trace shows that we have tar sitting in balance_dirty_pages and > >we have the single delalloc worker doing requests. The other delalloc > >workers don't show up at all. > > > >So either they are earlier in the trace or they disappeared somehow. > >I'll definitely need the full trace if you can send it. > > I've got the full trace now. It's pretty big (430KB), so I've put it > on the web. > > Here's the state before switching to one thread > http://www-xray.ast.cam.ac.uk/~jss/data/btrfs-before.txt > > Here it is after it has switched to one thread: > http://www-xray.ast.cam.ac.uk/~jss/data/btrfs-after.txt According to this you've only got one delalloc worker. That would explain it. Could you please confirm with ps? You might be hitting a problem Josef sent patches for, I'll dig in. -chris -- 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
