Re: [PATCH] RFC: hung task: Check specific tasks for long uninterruptible sleep state

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From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] RFC: hung task: Check specific tasks for long uninterruptible sleep state
Date	Tue, 22 Aug 2017 22:40:02 +0200
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On Mon, Aug 21, 2017 at 03:55:53PM +0530, Imran Khan wrote:
> khungtask by default monitors either all tasks or no tasks at all
> for long unterruptible sleeps.
> For Android like environments this arrangement is not optimal because
> on one hand it may be permissible to have some background(bg) task
> in uninterruptible sleep state for long duration while on the other
> hand it may not be permissible to have some foreground(fg) task like
> surfaceflinger in uninterruptible sleep state for long duration.

How are you getting tasks in UNINTERRUPTIBLE state for a long time to
begin with? That's not a good thing, background or not.

> So it would be good to have some arrangement so that few specified tasks
> can be monitored by khungtaskd, on a need basis.
> This change introduces a sysctl option, /proc/sys/kernel/
> hung_task_check_selected, to enable monitoring of selected tasks using
> khungtask daemon. If this sysctl option is enabled then only the tasks
> specified in /proc/hung_task_monitor_list are monitored otherwise all
> tasks are monitored, just like the default case.

That's horrible. Why not a file in /proc/$PID/ that excludes it from
things?

Thread

[PATCH] RFC: hung task: Check specific tasks for long uninterruptible sleep state Imran Khan <kimran@codeaurora.org> - 2017-08-21 12:30 +0200
  RE: [PATCH] RFC: hung task: Check specific tasks for long  uninterruptible sleep state "Zhang, Shile (NSB - CN/Hangzhou)" <shile.zhang@nokia-sbell.com> - 2017-08-22 04:00 +0200
    Re: [PATCH] RFC: hung task: Check specific tasks for long  uninterruptible sleep state Imran Khan <kimran@codeaurora.org> - 2017-08-22 08:10 +0200
      RE: [PATCH] RFC: hung task: Check specific tasks for long  uninterruptible sleep state "Zhang, Shile (NSB - CN/Hangzhou)" <shile.zhang@nokia-sbell.com> - 2017-08-22 08:50 +0200
  Re: [PATCH] RFC: hung task: Check specific tasks for long  uninterruptible sleep state Peter Zijlstra <peterz@infradead.org> - 2017-08-22 22:40 +0200
    Re: [PATCH] RFC: hung task: Check specific tasks for long  uninterruptible sleep state Imran Khan <kimran@codeaurora.org> - 2017-08-23 14:30 +0200

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