From: "Srivatsa S. Bhat" <srivatsa@csail.mit.edu>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: linux-fsdevel@vger.kernel.org,
linux-block <linux-block@vger.kernel.org>,
linux-ext4@vger.kernel.org, cgroups@vger.kernel.org,
kernel list <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
Jeff Moyer <jmoyer@redhat.com>, Theodore Ts'o <tytso@mit.edu>,
amakhalov@vmware.com, anishs@vmware.com, srivatsab@vmware.com,
Ulf Hansson <ulf.hansson@linaro.org>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller
Date: Sun, 2 Jun 2019 00:04:34 -0700 [thread overview]
Message-ID: <6a6f4aa4-fc95-f132-55b2-224ff52bd2d8@csail.mit.edu> (raw)
In-Reply-To: <7B74A790-BD98-412B-ADAB-3B513FB1944E@linaro.org>
On 5/30/19 3:45 AM, Paolo Valente wrote:
>
>
>> Il giorno 30 mag 2019, alle ore 10:29, Srivatsa S. Bhat <srivatsa@csail.mit.edu> ha scritto:
>>
[...]
>>
>> Your fix held up well under my testing :)
>>
>
> Great!
>
>> As for throughput, with low_latency = 1, I get around 1.4 MB/s with
>> bfq (vs 1.6 MB/s with mq-deadline). This is a huge improvement
>> compared to what it was before (70 KB/s).
>>
>
> That's beautiful news!
>
> So, now we have the best of the two worlds: maximum throughput and
> total control on I/O (including minimum latency for interactive and
> soft real-time applications). Besides, no manual configuration
> needed. Of course, this holds unless/until you find other flaws ... ;)
>
Indeed, that's awesome! :)
>> With tracing on, the throughput is a bit lower (as expected I guess),
>> about 1 MB/s, and the corresponding trace file
>> (trace-waker-detection-1MBps) is available at:
>>
>> https://www.dropbox.com/s/3roycp1zwk372zo/bfq-traces.tar.gz?dl=0
>>
>
> Thank you for the new trace. I've analyzed it carefully, and, as I
> imagined, this residual 12% throughput loss is due to a couple of
> heuristics that occasionally get something wrong. Most likely, ~12%
> is the worst-case loss, and if one repeats the tests, the loss may be
> much lower in some runs.
>
Ah, I see.
> I think it is very hard to eliminate this fluctuation while keeping
> full I/O control. But, who knows, I might have some lucky idea in the
> future.
>
:)
> 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!
> [1] https://algo.ing.unimo.it/people/paolo/disk_sched/results.php
> [2] https://www.linaro.org/blog/io-bandwidth-management-for-production-quality-services/
>
>> Thank you so much for your tireless efforts in fixing this issue!
>>
>
> I did enjoy working on this with you: your test case and your support
> enabled me to make important improvements. So, thank you very much
> for your collaboration so far,
> Paolo
My pleasure! :)
Regards,
Srivatsa
VMware Photon OS
next prev parent reply other threads:[~2019-06-02 7:35 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-17 22:16 CFQ idling kills I/O performance on ext4 with blkio cgroup controller Srivatsa S. Bhat
2019-05-18 18:39 ` Paolo Valente
2019-05-18 19:28 ` Theodore Ts'o
2019-05-20 9:15 ` Jan Kara
2019-05-20 10:45 ` Paolo Valente
2019-05-21 16:48 ` Theodore Ts'o
2019-05-21 18:19 ` Josef Bacik
2019-05-21 19:10 ` Theodore Ts'o
2019-05-20 10:38 ` Paolo Valente
2019-05-21 7:38 ` Andrea Righi
2019-05-18 20:50 ` Srivatsa S. Bhat
2019-05-20 10:19 ` Paolo Valente
2019-05-20 22:45 ` Srivatsa S. Bhat
2019-05-21 6:23 ` Paolo Valente
2019-05-21 7:19 ` Srivatsa S. Bhat
2019-05-21 9:10 ` Jan Kara
2019-05-21 16:31 ` Theodore Ts'o
2019-05-21 11:25 ` Paolo Valente
2019-05-21 13:20 ` Paolo Valente
2019-05-21 16:21 ` Paolo Valente
2019-05-21 17:38 ` Paolo Valente
2019-05-21 22:51 ` Srivatsa S. Bhat
2019-05-22 8:05 ` Paolo Valente
2019-05-22 9:02 ` Srivatsa S. Bhat
2019-05-22 9:12 ` Paolo Valente
2019-05-22 10:02 ` Srivatsa S. Bhat
2019-05-22 9:09 ` Paolo Valente
2019-05-22 10:01 ` Srivatsa S. Bhat
2019-05-22 10:54 ` Paolo Valente
2019-05-23 2:30 ` Srivatsa S. Bhat
2019-05-23 9:19 ` Paolo Valente
2019-05-23 17:22 ` Paolo Valente
2019-05-23 23:43 ` Srivatsa S. Bhat
2019-05-24 6:51 ` Paolo Valente
2019-05-24 7:56 ` Paolo Valente
2019-05-29 1:09 ` Srivatsa S. Bhat
2019-05-29 7:41 ` Paolo Valente
2019-05-30 8:29 ` Srivatsa S. Bhat
2019-05-30 10:45 ` Paolo Valente
2019-06-02 7:04 ` Srivatsa S. Bhat [this message]
2019-06-11 22:34 ` Srivatsa S. Bhat
2019-06-12 13:04 ` Jan Kara
2019-06-12 19:36 ` Srivatsa S. Bhat
2019-06-13 6:02 ` Greg Kroah-Hartman
2019-06-13 19:03 ` Srivatsa S. Bhat
2019-06-13 8:20 ` Jan Kara
2019-06-13 19:05 ` Srivatsa S. Bhat
2019-06-13 8:37 ` Jens Axboe
2019-06-13 5:46 ` Paolo Valente
2019-06-13 19:13 ` Srivatsa S. Bhat
2019-05-23 23:32 ` Srivatsa S. Bhat
2019-05-30 8:38 ` Srivatsa S. Bhat
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6a6f4aa4-fc95-f132-55b2-224ff52bd2d8@csail.mit.edu \
--to=srivatsa@csail.mit.edu \
--cc=amakhalov@vmware.com \
--cc=anishs@vmware.com \
--cc=axboe@kernel.dk \
--cc=cgroups@vger.kernel.org \
--cc=jack@suse.cz \
--cc=jmoyer@redhat.com \
--cc=linus.walleij@linaro.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=paolo.valente@linaro.org \
--cc=srivatsab@vmware.com \
--cc=tytso@mit.edu \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).