linux-kernel - Re: deadlock in scheduler enabling HRTICK feature

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Message-ID: <51CA0980.8010409@gmail.com>
Date:	Tue, 25 Jun 2013 15:20:00 -0600
From:	David Ahern <dsahern@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: deadlock in scheduler enabling HRTICK feature

On 6/25/13 3:17 PM, Peter Zijlstra wrote:
> On Tue, Jun 25, 2013 at 03:05:38PM -0600, David Ahern wrote:
>> Peter/Ingo:
>>
>> I can reliably cause a deadlock in the scheduler by enabling the HRTICK
>> feature. I first hit the problem with 2.6.27 but have been able to reproduce
>> it with newer kernels. I have not tried top of Linus' tree, so perhaps this
>> has been fixed in 3.10.
>
> Yeah, I know.. its been on the todo list forever but its never been
> important. Its disabled by default and all sched debug features are for
> those brave enough to keep the pieces ;-)
>

Not a whole to of pieces to keep.

What is the expectation that the feature provides? not a whole lot of 
documentation on it. I walked down the path wondering if it solved an 
odd problem we are seeing with the CFS in 2.6.27 kernel.

David
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