Re: [Qemu-devel] [PATCH] qcow2: avoid lseek on block_status if possible

[Kevin Wolf]

Am 25.01.2019 um 15:36 hat Vladimir Sementsov-Ogievskiy geschrieben:
> 25.01.2019 17:21, Vladimir Sementsov-Ogievskiy wrote:
> > Results on tmpfs:
> > cached is lseek cache by Kevin
> > detect is this patch
> > no lseek is just remove block_status query on bs->file->bs in
> >           bdrv_co_block_status
> > 
> >      +---------------------+--------+--------+--------+----------+
> >      |                     | master | cached | detect | no lseek |
> >      +---------------------+--------+--------+--------+----------+
> >      | test.qcow2          | 80     | 40     | 0.169  | 0.162    |
> >      +---------------------+--------+--------+--------+----------+
> >      | test_forward.qcow2  | 79     | 0.171  | 0.169  | 0.163    |
> >      +---------------------+--------+--------+--------+----------+
> >      | test_prealloc.qcow2 | 0.054  | 0.053  | 0.055  | 0.263    |
> >      +---------------------+--------+--------+--------+----------+
> 
> Forgot to say, tests by Kevin from branch
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg05463.html
> 
> Hmm. Don't we have something like tests/qemu-iotests, but for performance?
> So, all these small pretty tests we have in mailing list may go as git 
> patches?

Sounds like a good idea. Maybe we can just create a new subdirectory
qemu-iotests/perf/ and put some benchmark scripts there?

Of course, they wouldn't be able to tell PASS/FAIL like normal
qemu-iotests and so they wouldn't be integrated into the normal
qemu-iotests suite, but just return numbers that can be compared with
different setups or revisions on the same machine.

Kevin