Re: Performance degradation

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On 22 September 2010 01:02, Chris Mason <chris.mason@xxxxxxxxxx> wrote:
> On Tue, Sep 21, 2010 at 12:27:03AM -0400, Dave Cundiff wrote:
>> On Mon, Sep 20, 2010 at 9:19 PM, K. Richard Pixley <rich@xxxxxxxx> wrote:
>> > Do you have any kernel processes running constantly?  Any taking near 100% of a CPU?
>> >
>> > --rich
>> >
>>
>> Now that I look again, it seems that the btrfs-cleaner process is
>> still running. CPU isn't much of an issue on this box. Its a dual quad
>> E5620. 8 cores, 16 threads.
>> Looks like most of my load is wait from the cleaner process hammering
>> the disks. I deleted about 10 snapshots I think. Should this take 4
>> days to clean up from that?
>
> It shouldn't but it depends on how much metadata we have to read in to
> process the snapshots.  Could you do a few sysrq-w?  We'll see where you
> are spending your time based on the traces.

Also, using 'perf' may give a good picture of where the time is spent, eg:

$ sudo perf record -a sleep 20
$ sudo perf report | tee profile.txt
-- 
Daniel J Blueman
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