From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-block <linux-block@vger.kernel.org>,
SIMONE RICHETTI <206161@studenti.unimore.it>
Subject: Re: Injecting delays into block layer
Date: Fri, 06 Dec 2019 20:50:25 +0100 [thread overview]
Message-ID: <9f0b26c537f298defc56b7e39468db22@natalenko.name> (raw)
In-Reply-To: <942604AE-5A91-4E05-869F-74A7EAC5A247@linaro.org>
Hello.
On 06.12.2019 17:17, Paolo Valente wrote:
> Simone (in CC) and I have worked a little bit on reproducing the I/O
> freeze you report. Simone made a small change in SCSI_debug, which
> makes the latter serve I/O with a highly varying random delay (100ms -
> 1s), about twice a second.
>
> Then, to generate some fluctuating and heavy I/O, he ran the
> comm_startup_lat.sh script of my S suite with SCSI_debug a few times.
> Unfortunately, he didn't succeed in reproducing the problem. If you
> want, we can send you a patch with his change for SCSI_debug.
>
> Any news on your side?
I was playing with dm-delay in an isolated VM, but so far got no luck.
I'll try to find another way to trigger this (if the bug is still
present in 5.4) and get back to you in case of success.
For me it is a rare occurrence in production, and since I've upgraded to
5.4 and disabled BFQ I haven't seen any at all. At this point I'm not
even sure what I'm looking at. I'll try to re-enable BFQ soon to stress
my production VMs again.
Thank you.
--
Oleksandr Natalenko (post-factum)
next prev parent reply other threads:[~2019-12-06 19:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-21 7:13 Injecting delays into block layer Oleksandr Natalenko
2019-11-21 8:00 ` Paolo Valente
2019-12-06 16:17 ` Paolo Valente
2019-12-06 19:50 ` Oleksandr Natalenko [this message]
2019-12-23 0:10 ` Oleksandr Natalenko
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=9f0b26c537f298defc56b7e39468db22@natalenko.name \
--to=oleksandr@natalenko.name \
--cc=206161@studenti.unimore.it \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=paolo.valente@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