Re: [patch] latency tracer, 2.6.15-rc7

[Dipankar Sarma]

On Tue, Jan 03, 2006 at 05:28:15AM -0800, David Lang wrote:
> On Tue, 3 Jan 2006, Dipankar Sarma wrote:
> 
> >I do agree that the two layers of batching really makes things
> >subtle. I think the best we can do is to figure out some way of
> >automatic throttling in RCU and forced quiescent state under extreme
> >conditions. That way we will have less dependency on softirq
> >throttling.
> 
> would it make sense to have the RCU subsystems with a threshold so that 
> when more then X items are outstanding they trigger a premption of all 
> other CPU's ASAP (forceing the scheduling break needed to make progress on 
> clearing RCU)? This wouldn't work in all cases, but it could significantly 
> reduce the problem situations.

Yes, I think it would make sense to try something like that. See Paul's earlier
mail in this thread for an example code snippet.

Thanks
Dipankar
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