Re: [PATCH] xfs: account extra freespace btree splits for multiple allocations

Gao Xiang
2022-11-23T00:38:48Z

Sorry I sent out a staging reply, please ignore this.

On Wed, Nov 23, 2022 at 08:33:02AM +0800, Gao Xiang wrote:
> On Tue, Nov 22, 2022 at 06:03:03PM +0800, Oliver Sang wrote:
> > hi Gao Xiang,
> >
> > On Tue, Nov 22, 2022 at 09:33:38AM +0800, Gao Xiang wrote:
> > > On Tue, Nov 22, 2022 at 09:09:34AM +0800, kernel test robot wrote:
> > > >
> > > > please be noted we noticed Gao Xiang and Dave Chinner have already had lots of
> > > > discussion around this patch, which seems there is maybe new version later.
> > > > we just sent out this report FYI the possible performance impact of this patch.
> > > >
> > > >
> > > > Greeting,
> > > >
> > > > FYI, we noticed a -15.1% regression of fxmark.ssd_xfs_MWCM_72_directio.works/sec due to commit:
> > >
> > > Thanks for your report!
> > >
> > > At a glance, I have no idea why this commit can have performance
> > > impacts. Is the result stable?
> >
> > in our tests, the result is quite stable.
> > 45589 -15.1% 38687 ± 2% fxmark.ssd_xfs_MWCM_72_directio.works/sec
> >
> > and detail data is as below:
> > for this commit:
> > "fxmark.ssd_xfs_MWCM_72_directio.works/sec": [
> > 39192.224368,
> > 39665.690567,
> > 38980.680601,
> > 37298.99538,
> > 37483.256377,
> > 39504.606569
> > ],
> >
> > for parent:
> > "fxmark.ssd_xfs_MWCM_72_directio.works/sec": [
> > 45381.458009,
> > 45314.376204,
> > 45724.688965,
> > 45751.955937,
> > 45614.323267,
> > 45747.216475
> > ],
> >
> >
> > if you still have concern, we could rerun tests. Thanks!
>
> According to the report, I can see:
> 67262 -29.6% 47384 ± 7% fxmark.ssd_xfs_MWCM_18_directio.works/sec
> 52786 -15.6% 44567 ± 4% fxmark.ssd_xfs_MWCM_1_directio.works/sec
> 63189 -23.3% 48486 ± 5% fxmark.ssd_xfs_MWCM_2_directio.works/sec

I meant allocation strategy change may cause this, but I didn't think it
could cause such impact. I will reconfirm on my own side as well.

Thanks,
Gao Xiang