Re: [RFC] ACPI, APEI, Generic Hardware Error Source (GHES) injectingsupport

From: Ingo Molnar
Date: Fri May 20 2011 - 07:53:34 EST

* Borislav Petkov <bp@xxxxxxxxx> 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.


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