Re: deadlock in scheduler enabling HRTICK feature

From: David Ahern
Date: Tue Jun 25 2013 - 17:20:12 EST


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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