From: Daniel Walker <dwalker@fifo99.com>
To: Mandeep Singh Baines <msb@google.com>
Cc: fweisbec@gmail.com, msb@chromium.org, sshaiju@mvista.com,
mingo@elte.hu, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: hung_task checking and sys_sync
Date: Tue, 12 Jun 2012 15:34:22 -0700 [thread overview]
Message-ID: <20120612223422.GB13492@fifo99.com> (raw)
In-Reply-To: <20120612222912.GB16381@google.com>
On Tue, Jun 12, 2012 at 03:29:12PM -0700, Mandeep Singh Baines wrote:
>
> But the time is not unbounded. You could mask the hung_task_detector for
> this case but then you lose the ability to catch bugs in this code path.
>
> The timeout is configurable via /proc/sys/kernel/hung_task_timeout_secs.
> Can you bump up the value at boot via sysctl.conf?
Maybe, but I'm wondering if these types should just be stopped because Andrew
had complained about them already.
> > Has there been any commit that disable these messages bdi_sched_wait?
> >
>
> No. There is no mechanism to disable hung_task for a specific code path.
> We do skip processes if PF_PROZEN or PF_FROZEN_SKIP is set but that is
> really a different situation where the wait is unbounded.
There is presidence for this type of change,
Author: Mark Lord <kernel@teksavvy.com>
Date: Fri Sep 24 09:51:13 2010 -0400
block: Prevent hang_check firing during long I/O
During long I/O operations, the hang_check timer may fire,
trigger stack dumps that unnecessarily alarm the user.
Eg. hdparm --security-erase NULL /dev/sdb ## can take *hours* to complete
So, if hang_check is armed, we should wake up periodically
to prevent it from triggering. This patch uses a wake-up interval
equal to half the hang_check timer period, which keeps overhead low enough.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
next prev parent reply other threads:[~2012-06-12 22:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-12 22:09 hung_task checking and sys_sync Daniel Walker
2012-06-12 22:29 ` Mandeep Singh Baines
2012-06-12 22:34 ` Daniel Walker [this message]
2012-06-12 22:45 ` Mandeep Baines
2012-06-12 22:57 ` Daniel Walker
2012-06-13 1:03 ` Muthu Kumar
2012-06-13 15:43 ` Daniel Walker
2012-06-13 3:02 ` Sadasivan Shaiju
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