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Message-ID: <20110520115307.GG14745@elte.hu>
Date: Fri, 20 May 2011 13:53:07 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Borislav Petkov <bp@...en8.de>, Don Zickus <dzickus@...hat.com>,
Huang Ying <ying.huang@...el.com>, Len Brown <lenb@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andi Kleen <andi@...stfloor.org>,
"Luck, Tony" <tony.luck@...el.com>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: Re: [RFC] ACPI, APEI, Generic Hardware Error Source (GHES) injecting
support
* Borislav Petkov <bp@...en8.de> wrote:
> On Tue, May 17, 2011 at 09:18:03PM +0200, Ingo Molnar wrote:
> > So for example [sufficienty privileged] user-space could inject *any*
> > perf event - for example a PERF_COUNT_HW_CACHE_MISSES event (for test
> > purposes) and any tooling that runs could not tell apart this injected
> > event from a real event.
>
> Yeah about that, I was recently speculating how that would work. So do we do
>
> $ perf record ...
>
> in the one xterm, and, in the other,
>
> $ perf inject
>
> so that while recording, we can inject some events from userspace? Or
> do we inject it, it gets buffered somewhere in the meantime and then
> the next perf record session sees it along with the remaining injection
> events?
Well, for persistent events there would be interim buffering even if there's no
observation going on anywhere. I.e. there's always an 'observer' of events.
For non-persistent events, if they are injected, then they are like trace
events for which nobody is interested in: they are lost.
Thanks,
Ingo
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