Messages in this thread | | | Subject | Re: [PATCH] x86 fixes for 3.3 impacting distros (v1). | From | "H. Peter Anvin" <> | Date | Mon, 20 Feb 2012 17:38:52 -0800 |
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Odd... given that that is the NOP recommended by AMD.
Steven Rostedt <rostedt@goodmis.org> wrote:
>On Fri, 2012-02-10 at 10:34 -0500, Konrad Rzeszutek Wilk wrote: >> 66 66 66 90 data32 data32 xchg %ax,%ax >> >> [the 66 66 .. is 'nop']. Looks good right? Well, it does work very >well on Intel >> (used an i3 2100), but on AMD A8-3850 it hits a performance wall - >that I found out >> is a result of CONFIG_FUNCTION_TRACER (too many nops??) being >compiled in (but the tracer >> is set to the default 'nop'). If I disable that specific config >option the numbers >> are the same as the baseline (with CONFIG_FUNCTION_TRACER disabled) >on the AMD box. >> Interestingly enough I only see these on AMD machines - not on the >Intel ones. > >All paravirt ops should be labeled with "notrace" so that function >tracer does not trace those functions. Have you annotated your new >paravirt ops with notrace? > >-- Steve
-- Sent from my mobile phone. Please excuse my brevity and lack of formatting.
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