Re: cosd death by oom-killer

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Hi Sage,

So I've made a little progress on this.

I think I have a smoking gun: the "buf" column of
/var/log/ceph/stat/osd0 shows that bufferlist memory
grows to several GiB, and stays that way until the cosd
process is killed via the oom-killer.

I also think that my test configuration contributes:
my client host is several years newer than the server
host, and my network is 10 Gb/s.

I've got a little patch that puts a Pipe reader to
sleep for a bit if the bufferlist memory use gets too
big, and it completely solves my problem.  With it my
cosd RSS hovers in the few hundred MiB range.  I doubt if
it is the correct final solution, but it surely seems
to point in the direction of one.

I'll post it as a reply to this email; please let me know
what you think.

-- Jim

On Wed, 2010-05-26 at 17:28 -0600, Sage Weil wrote:
> Hi Jim,
> 
> Interesting.. we saw a similar report on irc.  Can you add
> 
> 	debug osd = 20
> 	debug filestore = 20
> 	debug journal = 20
> 	debug ms = 1
> 
> to your [osd] section, reproduce the crash, and then send us the osd log?  
> (It's at /var/log/ceph/osd$id, unless you've put it somewhere else.)
> 
> Thanks!
> sage
> 
> 
> On Wed, 26 May 2010, Jim Schutt wrote:
> 
> > Hi,
> > 
> > I'm running an interesting test case where I can
> > cause an instance of cosd to use all available memory on
> > its server.
> > 
> > On the server side I'm running the testing branch (at 
> > commit  817495d2).  On the client side I'm running the
> > for-linus branch (at commit 240ed68e).  Client and server
> > are both CentOS 5.5.
> > 
> > My filesystem has one monitor daemon, two mds daemons,
> > and one osd daemon, all running on one system with 4 GiB
> > memory.  I'm running with no swap, because otherwise 
> > during this test the system swaps like mad and becomes
> > unresponsive.  The swapping is what made me look deeper.
> > 
> > I mount this filesystem on a client system, then try to 
> > create a 16 GiB file on it using dd.  While creating
> > the file I watch the server with top, and see that both
> > the virtual memory use and resident set size of the
> > cosd instance grow to ~4 GiB, and a short time later cosd 
> > dies by oom-killer:
> > 
> > May 26 16:12:28 sasa008 kernel: [  902.544418] Killed process 6621 (cosd) vsz:4319672kB, anon-rss:3832152kB, file-rss:208kB
> > 
> > The osd has a 100 GiB partition for its data.
> > 
> > Am I maybe doing something wrong? 
> > Is there anything else I can do to help debug this?
> > 
> > Thanks -- Jim
> > 
> > 
> > 
> > --
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> > 
> > 
> 


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