[dm-devel] [RFC PATCH 0/4] dm mpath: vastly improve blk-mq IO performance
Mike Snitzer
snitzer at redhat.com
Fri Apr 1 13:22:19 UTC 2016
On Fri, Apr 01 2016 at 4:12am -0400,
Johannes Thumshirn <jthumshirn at suse.de> wrote:
> On 2016-03-31 22:04, Mike Snitzer wrote:
> >I developed these changes some weeks ago but have since focused on
> >regression and performance testing on larger NUMA systems.
> >
> >For regression testing I've been using mptest:
> >https://github.com/snitm/mptest
> >
> >For performance testing I've been using a null_blk device (with
> >various configuration permutations, e.g. pinning memory to a
> >particular NUMA node, and varied number of submit_queues).
> >
> >By eliminating multipath's heavy use of the m->lock spinlock in the
> >fast IO paths serious performance improvements are realized.
>
> Hi Mike,
>
> Are this the patches you pointed Hannes to?
>
> If yes, please add my Tested-by: Johannes Thumshirn <jthumshirn at suse.de>
No they are not.
Hannes seems to have last pulled in my DM mpath changes that (ab)used RCU.
I ended up dropping those changes and this patchset is the replacement.
So please retest with this patchset (I know you guys have a large setup
that these changes are very relevant for). If you could actually share
_how_ yo've tested that'd help me understand how these changes are
holding up. So far all looks good for me...
Mike
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