Re: commit 01e99aeca397 causes longer runtime of block/004

Shinichiro Kawasaki
2020-03-04T06:11:41Z

On Mar 04, 2020 / 11:46, Ming Lei wrote:
> On Wed, Mar 04, 2020 at 02:38:43AM +0000, Shinichiro Kawasaki wrote:
> > I noticed that blktests block/004 takes longer runtime with 5.6-rc4 than
> > 5.6-rc3, and found that the commit 01e99aeca397 ("blk-mq: insert passthrough
> > request into hctx->dispatch directly") triggers it.
> >
> > The longer runtime was observed with dm-linear device which maps SATA SMR HDD
> > connected via AHCI. It was not observed with dm-linear on SAS/SATA SMR HDDs
> > connected via SAS-HBA. Not observed with dm-linear on non-SMR HDDs either.
> >
> > Before the commit, block/004 took around 130 seconds. After the commit, it takes
> > around 300 seconds. I need to dig in further details to understand why the
> > commit makes the test case longer.
> >
> > The test case block/004 does "flush intensive workload". Is this longer runtime
> > expected?
>
> The following patch might address this issue:
>
> https://lore.kernel.org/linux-block/20200207190416.99928-1-sqazi@google.com/#t
>
> Please test and provide us the result.
>
> thanks,
> Ming
>

Hi Ming,

I applied the patch to 5.6-rc4 but I observed the longer runtime of block/004.
Still it takes around 300 seconds.

--
Best Regards,
Shin'ichiro Kawasaki