Messages in this thread | | | Date | Wed, 28 Sep 2011 09:51:33 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [V6][PATCH 4/6] x86, nmi: add in logic to handle multiple events and unknown NMIs |
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On 09/28/2011 05:37 AM, Don Zickus wrote: > On Wed, Sep 28, 2011 at 12:31:40PM +0200, Robert Richter wrote: >> On 23.09.11 15:17:13, Don Zickus wrote: >>> @@ -89,6 +89,15 @@ static int notrace __kprobes nmi_handle(unsigned int type, struct pt_regs *regs) >>> >>> handled += a->handler(type, regs); >>> >>> + /* >>> + * Optimization: only loop once if this is not a >>> + * back-to-back NMI. The idea is nothing is dropped >>> + * on the first NMI, only on the second of a back-to-back >>> + * NMI. No need to waste cycles going through all the >>> + * handlers. >>> + */ >>> + if (!b2b && handled) >>> + break; >> I don't think we can leave this in. As said, there are cases that 2 >> nmis trigger but the handler is called only once. Only the first would >> be handled then, and the second get lost cause there is no 2nd nmi >> call. > Right. Avi, Jeremy what was your objection that needed this optimization > in the first place?
My only interest in the NMI code is its use of spinlocks, which seem inappropriate.
J
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