LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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>,
	jmoyer@redhat.com, Theodore Ts'o <tytso@mit.edu>,
	amakhalov@vmware.com, anishs@vmware.com, srivatsab@vmware.com
Subject: Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller
Date: Thu, 30 May 2019 01:29:23 -0700	[thread overview]
Message-ID: <0d6e3c02-1952-2177-02d7-10ebeb133940@csail.mit.edu> (raw)
In-Reply-To: <FFA44D26-75FF-4A8E-A331-495349BE5FFC@linaro.org>

On 5/29/19 12:41 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 29 mag 2019, alle ore 03:09, Srivatsa S. Bhat <srivatsa@csail.mit.edu> ha scritto:
>>
>> On 5/23/19 11:51 PM, Paolo Valente wrote:
>>>
>>>> Il giorno 24 mag 2019, alle ore 01:43, Srivatsa S. Bhat <srivatsa@csail.mit.edu> ha scritto:
>>>>
>>>> When trying to run multiple dd tasks simultaneously, I get the kernel
>>>> panic shown below (mainline is fine, without these patches).
>>>>
>>>
>>> Could you please provide me somehow with a list *(bfq_serv_to_charge+0x21) ?
>>>
>>
>> Hi Paolo,
>>
>> Sorry for the delay! Here you go:
>>
>> (gdb) list *(bfq_serv_to_charge+0x21)
>> 0xffffffff814bad91 is in bfq_serv_to_charge (./include/linux/blkdev.h:919).
>> 914
>> 915	extern unsigned int blk_rq_err_bytes(const struct request *rq);
>> 916
>> 917	static inline unsigned int blk_rq_sectors(const struct request *rq)
>> 918	{
>> 919		return blk_rq_bytes(rq) >> SECTOR_SHIFT;
>> 920	}
>> 921
>> 922	static inline unsigned int blk_rq_cur_sectors(const struct request *rq)
>> 923	{
>> (gdb)
>>
>>
>> For some reason, I've not been able to reproduce this issue after
>> reporting it here. (Perhaps I got lucky when I hit the kernel panic
>> a bunch of times last week).
>>
>> I'll test with your fix applied and see how it goes.
>>
> 
> Great!  the offending line above gives me hope that my fix is correct.
> If no more failures occur, then I'm eager (and a little worried ...)
> to see how it goes with throughput :)
> 

Your fix held up well under my testing :)

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).

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 so much for your tireless efforts in fixing this issue!

Regards,
Srivatsa
VMware Photon OS

  reply	other threads:[~2019-05-30  8:29 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-17 22:16 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 [this message]
2019-05-30 10:45                                         ` Paolo Valente
2019-06-02  7:04                                           ` Srivatsa S. Bhat
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=0d6e3c02-1952-2177-02d7-10ebeb133940@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=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 \
    --subject='Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller' \
    /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

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).