Re: [PATCH]: Fix bogus softlockup warning with sysrq-t
From: Jeremy Fitzhardinge
Date: Tue Mar 27 2007 - 01:43:44 EST
Prarit Bhargava wrote:
> There are some situations when soft lockup warnings are expected in the
> kernel. For example, when doing an alt-sysrq-t on a large number of processes,
> the dump to console can take a long time and the tasklist_lock is held over
> that period. This results in a bogus soft lockup warning.
>
Wouldn't it be better to just temporarily disable softlockups for the
duration?
> This patch reworks touch_softlockup_watchdog to touch ALL cpu's
> touch_timestamp. It also introduces touch_cpu_softlockup_watchdog to touch
> a single cpu's touch_timestamp.
Doesn't this mean that if one CPU gets locked up, it will be undetected
so long as some other CPU is making progress?
I have another pair of softlockup patches in which I try to address:
* ignoring time stolen by hypervisors
* threads going to sleep tickless for long periods of time
I could easy add a "global disable" function, which would allow long
sysrq messages, and it would help Thilo with his long flash update freezes.
J
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