[libvirt] blkio cgroup

[Dominik Klein]

Hi

so I ran these tests again. No patch applied yet. And - at least once -
it worked. I did everything exactly the same way as before. Since the
logs are 8 MB, even when best-bzip2'd, and I don't want everybody to
have to download these, I uploaded them to an external hoster:
http://www.megaupload.com/?d=SWKTC0V4

Traces were created with
blktrace -n 64 -b 16384 -d /dev/sdb -o - | blkparse -i -
blktrace -n 64 -b 16384 -d /dev/vdisks/kernel3 -o - | blkparse -i -

> Can you please apply attached patch. 

Unfortunately not. Cannot be applied to 2.6.37. I guess your source is
newer and I fail to find the places in the file to patch manually.

> This just makes CFQ output little
> more verbose and run the test again and capture the trace.
> 
> - Start the trace on /dev/sdb
> - Start the dd jobs in virt machines
> - Wait for system to hang
> - Press CTRL-C
> - Make sure there were no lost events otherwise increase the size and
>   number of buffers.

Tried that. Unfortunately, even with max buffer size of 16 M [1], this
leaves some Skips. I also tried to increase the number of buffers over
64, but that produced Oops'es.

However, I attached kernel3's blktrace of a case where the error
occured. Maybe you can read something from that.

> Can you also open tracing in another window and also trace one of the
> throttled dm deivces, say /dev/disks/kernel3. Following the same procedure
> as above. So let the two traces run in parallel.

So what next?

Regards
Dominik

[1]
http://git.kernel.org/?p=linux/kernel/git/axboe/blktrace.git;a=blob_plain;f=blktrace.c;hb=HEAD
and look for "Invalid buffer"
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: blktrace_kernel3
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20110223/5a353135/attachment-0003.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: blktrace_sdb
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20110223/5a353135/attachment-0004.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: vmstat
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20110223/5a353135/attachment-0005.ksh>