Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support to use NMI-safe methods
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- Subject: Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support to use NMI-safe methods
- From: "H. Peter Anvin" <hpa@xxxxxxxxx>
- Date: Mon, 15 Jun 2009 12:18:12 -0700
- Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>, Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, mingo@xxxxxxxxxx, paulus@xxxxxxxxx, acme@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, penberg@xxxxxxxxxxxxxx, vegard.nossum@xxxxxxxxx, efault@xxxxxx, jeremy@xxxxxxxx, npiggin@xxxxxxx, tglx@xxxxxxxxxxxxx, linux-tip-commits@xxxxxxxxxxxxxxx
- In-reply-to: <4A369E00.2090408@xxxxxxxxxx>
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Avi Kivity wrote:
> On 06/15/2009 10:02 PM, Peter Zijlstra wrote:
>> Ah, well, I have no idea who expensive cr2 is, if its like a regular
>> register then it should be fine. If however its tons more expensive then
>> we should really avoid it.
>
> IIRC it's pretty cheap, I measured it once when tuning the kvm context
> switch code. I don't recall the exact numbers.
>
Sounds like a win to me.
-hpa
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