Re: Updated performance results

[Steven Pratt <slpratt@austin.ibm.com>]

Eric Whitney wrote:
>
>
> Chris Mason wrote:
>> On Mon, Sep 14, 2009 at 04:41:48PM -0500, Steven Pratt wrote:
>>> Only bit of bad news is I did get one error that crashed the system
>>> on single threaded nocow run. So that data point is missing.
>>> Output below:
>>
>> I hope I've got this fixed.  If you pull from the master branch of
>> btrfs-unstable there are fixes for async thread races.  The single
>> patch I sent before is included, but not enough.
>
> Chris:
>
> FYI - all five of my test systems have now finished my standard test 
> cycle on the -unstable master branch, and I've not seen a single hang. 
> So, your fix for the async thread shutdown race seems to have fixed my 
> problems, even if Steve's still seeing trouble.
>
> I'll note that the running times for fsstress on some of my systems 
> have become rather longer with btrfs-unstable/master kernels - 3.5 
> rather than 2.5 hours on multidevice filesystems.  Running times on 
> single device filesystems are roughly the same.
>
> I'm going to start another set of tests for thoroughness unless you've 
> got more patches coming.
I've had some offline discussions with Chris, and it seems the problem 
is triggered by unmounting and re-mounting the file system between tests 
(but not running mkfs again).   I have also just verified that the 
problem does not occur if repeated tests are run without the unmount 
mount cycle.  So in case this is not clear:

mkfs
mount
create new files
run test
umount
mount
delete old files
create new files
run test
BUG

but..

mkfs
mount
create new files
run test
umount
mkfs           <------  differnet
mount
delete old files
create new files
run test
...
all is fine

or...

mkfs
mount
create new files
run test
# no mounts or mkfs here
delete old files
create new files
run test
...
all is fine

Steve


>
> Thanks,
> Eric
>
>>
>> -chris
>>