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>,
tytso@mit.edu
Subject: Re: Injecting delays into block layer
Date: Mon, 23 Dec 2019 01:10:20 +0100 [thread overview]
Message-ID: <21d34f9558a286c60352b5634f291f71@natalenko.name> (raw)
In-Reply-To: <942604AE-5A91-4E05-869F-74A7EAC5A247@linaro.org>
Hi.
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?
FWIW, I guess I'm safe to exclude BFQ at the moment since I've
encountered a very similar issue without having BFQ enabled.
Also, I think this might be unrelated to the block layer at all. I
suspect there's some race between MADV_MERGEABLE and MADV_DONTNEED since
this is what's hammering the affected tasks and what I see from the call
traces.
I'll investigate further and probably talk to MM people instead. Sorry
for the noise.
--
Oleksandr Natalenko (post-factum)
prev parent reply other threads:[~2019-12-23 0:10 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
2019-12-23 0:10 ` Oleksandr Natalenko [this message]
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=21d34f9558a286c60352b5634f291f71@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 \
--cc=tytso@mit.edu \
/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