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Message-ID: <20130626094634.GA29181@gmail.com>
Date: Wed, 26 Jun 2013 11:46:34 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Robert Richter <rric@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 00/14] perf, persistent: Kernel updates for perf tool
integration
* Borislav Petkov <bp@...en8.de> wrote:
> On Wed, Jun 26, 2013 at 10:12:23AM +0200, Robert Richter wrote:
> > We get a new fd by opening the persistent event with the syscall.
> > There would be 2 new ioctls:
> >
> > ioctl(fd, PERF_EVENT_IOC_DETACH, 0);
> > ioctl(fd, PERF_EVENT_IOC_ATTACH, 0);
> >
> > This would be fine and reuses existing infrastructure.
>
> Well, how are you going to say that you want to open an already existing
> persistent event or your want to create exactly the same persistent
> event? Are we even going to allow identical persistent events to
> coexist?
If already existing persistent events show up somewhere in sysfs (or in a
separate pseudofilesystem) then an open() of them [given sufficient
privileges of the caller, etc.] could attach to them.
Thanks,
Ingo
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