From: Chris Mason <chris.mason@oracle.com>
To: Jeremy Sanders <jeremy@jeremysanders.net>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Btrfs switches to using mostly one thread
Date: Fri, 9 Dec 2011 09:18:16 -0500 [thread overview]
Message-ID: <20111209141816.GA8971@shiny> (raw)
In-Reply-To: <4EE1F994.4060908@jeremysanders.net>
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
next prev parent reply other threads:[~2011-12-09 14:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-08 15:19 Btrfs switches to using mostly one thread Jeremy Sanders
2011-12-08 15:32 ` Chris Mason
2011-12-08 15:36 ` Jeremy Sanders
2011-12-08 16:57 ` Jeremy Sanders
2011-12-08 17:23 ` Chris Mason
2011-12-08 17:39 ` Jeremy Sanders
2011-12-08 20:11 ` Chris Mason
2011-12-09 12:05 ` Jeremy Sanders
2011-12-09 14:18 ` Chris Mason [this message]
2011-12-09 14:22 ` Jeremy Sanders
2011-12-09 12:15 ` Arne Jansen
2011-12-09 12:20 ` Jeremy Sanders
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20111209141816.GA8971@shiny \
--to=chris.mason@oracle.com \
--cc=jeremy@jeremysanders.net \
--cc=linux-btrfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox