From: Ritesh Raj Sarraf <rrs@researchut.com>
To: axboe@fb.com, linux-block@vger.kernel.org
Subject: wb-buf-throttle feedback
Date: Sat, 10 Sep 2016 00:30:58 +0530 [thread overview]
Message-ID: <1473447658.8897.13.camel@researchut.com> (raw)
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Hi Jens,
[Please CC me in replies. I'm not subscribed to the list]
Based on your announcement about the writeback patches, I have picked up your
changes for testing.
I tested it on a 4.7.3 stable kernel with patches applied from your axboe/wb-
buf-throttle-v4.7 branch.
Instead of the infamous dd use case, I picked up the other generic one i.e. to
build the linux kernel.
Machine config:
Intel(R) Core(TM) i5-4210U CPU @ 1.70GHzRAM: 8 GiB
Disk: Rotational SATA HDD Hitachi - 7200 RPM
The machine has 4 logical CPUs.
Unfortunately, the issue is still easily reproducible. Building a kernel with
defaults, which results in make -j4, ended up stalling the entire OS.
systemd-journald couldn't really log the messages because it too gets affected
by this writeback issue.
https://github.com/systemd/systemd/issues/1353
The only message it logged are:
Sep 07 16:43:12 chutzpah systemd-journald[348]: Runtime journal
(/run/log/journal/) is 8.0M, max 73.8M, 65.8M free.
Sep 07 16:43:13 chutzpah systemd-journald[348]: System journal
(/var/log/journal/) is 3.9G, max 4.0G, 7.7M free.
Sep 07 16:43:14 chutzpah systemd-journald[348]: Time spent on flushing to /var
is 1.790678s for 2 entries.
Sep 07 16:43:20 chutzpah systemd-journald[348]: Journal started
Sep 08 00:28:55 chutzpah systemd-journald[348]: Suppressed 454 messages from
/system.slice/laptop-mode.service
Sep 08 23:07:29 chutzpah systemd-journald[348]: Suppressed 79 messages from
/user.slice/user-1000.slice
Sep 09 19:48:02 chutzpah systemd-journald[28710]: System journal
(/var/log/journal/) is 4.0G, max 4.0G, 0B free.
Sep 09 19:49:45 chutzpah systemd-journald[5986]: System journal
(/var/log/journal/) is 4.0G, max 4.0G, 0B free.
Sep 09 19:50:07 chutzpah systemd-journald[5986]: Journal started
Sep 09 19:43:30 chutzpah systemd[1]: systemd-journald.service: Watchdog timeout
(limit 3min)!
Sep 09 19:43:30 chutzpah systemd[1]: systemd-journald.service: Killing process
348 (systemd-journal) with signal SIGABRT.
- -- Reboot --
Which is self-explanatory.
At this time, the easy way to workaround the bug is to spare some resources.
In the above use case of mine, I've been working it around by consuming lesser
resources than what the machine has.
So my successful kernel builds have been firing `make -j3` instead. Not
efficient but definitely better than bringing the entire OS to a halt.
- --
Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."
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next reply other threads:[~2016-09-09 19:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-09 19:00 Ritesh Raj Sarraf [this message]
2016-09-09 20:02 ` wb-buf-throttle feedback Jens Axboe
2016-09-09 20:19 ` Jens Axboe
2016-09-11 9:55 ` Ritesh Raj Sarraf
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