Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller

[Jan Kara <jack@suse.cz>]

On Tue 11-06-19 15:34:48, Srivatsa S. Bhat wrote:
> On 6/2/19 12:04 AM, Srivatsa S. Bhat wrote:
> > On 5/30/19 3:45 AM, Paolo Valente wrote:
> >>
> [...]
> >> At any rate, since you pointed out that you are interested in
> >> out-of-the-box performance, let me complete the context: in case
> >> low_latency is left set, one gets, in return for this 12% loss,
> >> a) at least 1000% higher responsiveness, e.g., 1000% lower start-up
> >> times of applications under load [1];
> >> b) 500-1000% higher throughput in multi-client server workloads, as I
> >> already pointed out [2].
> >>
> > 
> > I'm very happy that you could solve the problem without having to
> > compromise on any of the performance characteristics/features of BFQ!
> > 
> > 
> >> I'm going to prepare complete patches.  In addition, if ok for you,
> >> I'll report these results on the bug you created.  Then I guess we can
> >> close it.
> >>
> > 
> > Sounds great!
> >
> 
> Hi Paolo,
> 
> Hope you are doing great!
> 
> I was wondering if you got a chance to post these patches to LKML for
> review and inclusion... (No hurry, of course!)
> 
> Also, since your fixes address the performance issues in BFQ, do you
> have any thoughts on whether they can be adapted to CFQ as well, to
> benefit the older stable kernels that still support CFQ?

Since CFQ doesn't exist in current upstream kernel anymore, I seriously
doubt you'll be able to get any performance improvements for it in the
stable kernels...

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR