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Re: [Xen-devel] [PATCH, v2] reduce 'd' debug key's global impact

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH, v2] reduce 'd' debug key's global impact
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 06 May 2010 10:07:42 +0100
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>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 06.05.10 10:01 >>>
>Although I suppose the event-check vector has a cleaner interface for
>calling it and should be implemented for all architectures. If you add
>whatever new flag you need to irq_cpustat_t then it would be cheap to check,
>being a definite cache hit. I suppose each cpu would

Actually, in smp_event_check_interrupt(), irq_cpustat isn't being used
so far, so placing the new field there wouldn't be a definite cache hit.
Instead (if that has to remain, which I doubt) co-locating it with
__irq_regs would help here.

Otoh it seems like I will should add irq_enter()/irq_exit() now that the
function calls something non-trivial...

>check-and-check-and-clear it, and then set it for the next CPU when it is
>done. That doesn't sound too bad.


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