Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support to use NMI-safe methods
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
- Subject: Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support to use NMI-safe methods
- From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
- Date: Mon, 15 Jun 2009 21:02:41 +0200
- Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>, 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: <20090615185907.GF6520@Krystal>
- References: <tip-74193ef0ecab92535c8517f082f1f50504526c9b@xxxxxxxxxxxxxx> <alpine.LFD.2.01.0906151007560.3305@xxxxxxxxxxxxxxxxxxxxx> <20090615171845.GA7664@xxxxxxx> <alpine.LFD.2.01.0906151029160.3305@xxxxxxxxxxxxxxxxxxxxx> <4A369508.2090707@xxxxxxxxx> <20090615184858.GD6520@Krystal> <1245091917.6741.185.camel@laptop> <20090615185907.GF6520@Krystal>
On Mon, 2009-06-15 at 14:59 -0400, Mathieu Desnoyers wrote:
> * Peter Zijlstra (a.p.zijlstra@xxxxxxxxx) wrote:
> > On Mon, 2009-06-15 at 14:48 -0400, Mathieu Desnoyers wrote:
> > > we should not care that much about the performance hit of
> > > saving/restoring the cr2 register at each nmi entry/exit.
> >
> > But we do, perf counters very much cares about nmi performance.
> >
>
> To a point where it cannot afford a simple register save/restore ?
>
> There is "caring" and "_caring_". I am tempted to ask what NMI handler
> execution frequency you have in mind here to figure out if we are not
> trying to optimize sub-nanoseconds per minutes. ;)
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.
As to the freq, 100kHz would be nice ;-)
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
[Index of Archives]
[Linux Stable Commits]
[Linux Stable Kernel]
[Linux Kernel]
[Linux USB Devel]
[Linux Video &Media]
[Linux Audio Users]
[Yosemite News]
[Linux SCSI]