Messages in this thread | | | Subject | Re: smp.c && barriers (Was: [PATCH 1/4] generic-smp: remove single ipi fallback for smp_call_function_many()) | From | Suresh Siddha <> | Date | Wed, 18 Feb 2009 10:43:40 -0800 |
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On Wed, 2009-02-18 at 05:59 -0800, Nick Piggin wrote: > You're saying the problem is in generic_exec_single because I've > removed the smp_mb that inadvertently also serialises memory with > the x2apic on x86?
yes.
> > Indeed that could cause problems on some architectures which I > had hoped to avoid. So the patch is probably better off to first > add the smp_mb() to arch_send_call_function_xxx arch code, unless > it is immediately obvious or confirmed by arch maintainer that > such barrier is not required.
For x2apic specific operations we should add the smp_mb() sequence. But we need to make sure that we don't end up doing it twice (once in generic code and another in arch code) for all the ipi paths.
thanks, suresh
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