Re: freezer: should barriers be smp ?

From: Rafael J. Wysocki
Date: Wed Apr 13 2011 - 16:58:16 EST

On Wednesday, April 13, 2011, Mike Frysinger wrote:
> when we suspend/resume Blackfin SMP systems, we notice that the
> freezer code runs on multiple cores. this is of course what you want
> -- freeze processes in parallel. however, the code only uses non-smp
> based barriers which causes us problems ... our cores need software
> support to keep caches in sync, so our smp barriers do just that. but
> the non-smp barriers do not, and so the frozen/thawed processes
> randomly get stuck in the wrong task state.
> thinking about it, shouldnt the freezer code be using smp barriers ?

Yes, it should, but rmb() and wmb() are supposed to be SMP barriers.

Or do you mean something different?

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