Re: [GIT PULL] perf fixes

From: Ingo Molnar
Date: Thu Sep 12 2013 - 16:49:20 EST



* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Thu, Sep 12, 2013 at 1:33 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> >
> > Hm, just to make sure, are you running a (very fresh) kernel that has this
> > fix included:
> >
> > d008d5258e9c perf: Fix up MMAP2 buffer space reservation
>
> I've rebooted about five times since that report, so I'm not sure..
>
> [ Short time passes ]
>
> Hmm. That "reproducible" error is no longer reproducible for me on
> current git (68f0d9d92e54). So if you fixed something recently, it's
> possible I was running a pre-perf-pull kernel and an after-perf-pull
> "perf" binary.

Yeah, so I think prior merging d008d5258e9c you'd see those artifacts with
new, MMAP2-aware perf tooling. Both older kernels would work fine with any
version of the tooling, and old tooling would work fine. Only new tooling
used on a kernel within the breakage window would be exposed to this.

I think the window of breakage is relatively small (you managed to hit
it), but should we add a quirk for this?

Thanks,

Ingo
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