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[0/3] per-cpu in_flight counters for bio-based drivers

Message ID 20181128004211.368810060@debian.vm (mailing list archive)
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Series per-cpu in_flight counters for bio-based drivers | expand

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Mikulas Patocka Nov. 28, 2018, 12:42 a.m. UTC 
These are the patches for per-cpu in_flight counters.

Mikulas

Comments

Mike Snitzer Nov. 30, 2018, 2:43 p.m. UTC | #1 
On Tue, Nov 27 2018 at  7:42pm -0500,
Mikulas Patocka <mpatocka@redhat.com> wrote:

> These are the patches for per-cpu in_flight counters.

Do you have updated before vs after performance results for these
changes?

I'd imagine they are comparable to your previous run (though that run
included some other DM changes that I already staged).

Thanks,
Mike
Mike Snitzer Nov. 30, 2018, 3:50 p.m. UTC | #2 
On Fri, Nov 30 2018 at  9:43am -0500,
Mike Snitzer <snitzer@redhat.com> wrote:

> On Tue, Nov 27 2018 at  7:42pm -0500,
> Mikulas Patocka <mpatocka@redhat.com> wrote:
> 
> > These are the patches for per-cpu in_flight counters.
> 
> Do you have updated before vs after performance results for these
> changes?
> 
> I'd imagine they are comparable to your previous run (though that run
> included some other DM changes that I already staged).

Would like to see before vs after with:

http://git.kernel.dk/cgit/linux-block/log/?h=for-4.21/block
vs
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=block-dm-4.21-inflight

(block-dm-4.21-inflight is based on latest for-4.21/block -- and it
contains DM changes in front of the block changes from this thread; I'd
prefer Jens take the changes like this rather than leave DM in a bit of
a mess for me/us to have to cleanup later)
Mike Snitzer Nov. 30, 2018, 7:57 p.m. UTC | #3 
On Fri, Nov 30 2018 at 10:50am -0500,
Mike Snitzer <snitzer@redhat.com> wrote:

> On Fri, Nov 30 2018 at  9:43am -0500,
> Mike Snitzer <snitzer@redhat.com> wrote:
> 
> > On Tue, Nov 27 2018 at  7:42pm -0500,
> > Mikulas Patocka <mpatocka@redhat.com> wrote:
> > 
> > > These are the patches for per-cpu in_flight counters.
> > 
> > Do you have updated before vs after performance results for these
> > changes?
> > 
> > I'd imagine they are comparable to your previous run (though that run
> > included some other DM changes that I already staged).
> 
> Would like to see before vs after with:
> 
> http://git.kernel.dk/cgit/linux-block/log/?h=for-4.21/block
> vs
> https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=block-dm-4.21-inflight
> 
> (block-dm-4.21-inflight is based on latest for-4.21/block -- and it
> contains DM changes in front of the block changes from this thread; I'd
> prefer Jens take the changes like this rather than leave DM in a bit of
> a mess for me/us to have to cleanup later)

I ran the same fio test you did (in the previous thread where you did
the switch to percpu local to DM, rather than in block) _except_ I used
a ramdisk-based pmem device rather than a pure ramdisk:

fio --ioengine=psync --iodepth=1 --rw=read --bs=512 --direct=1 --numjobs=12 --time_based --runtime=10 --group_reporting --name=/dev/pmem0

2 6-core processors (w/ HT, so 24 logical cpus):

/dev/pmem0                                        14.6M
/dev/pmem0 with percpu counters                   14.8M
/dev/mapper/linear                                4736k
/dev/mapper/linear with percpu counters           4595k

It is only after I apply this commit that I can realize a big
performance win:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=block-dm-4.21-inflight&id=335b41c7513110b1519d8a93d412c138bf671263

/dev/mapper/linear with percpu + pending removed  11.2M