From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Borislav Petkov <bp@suse.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX
Date: Tue, 14 Feb 2017 19:38:07 +0100 [thread overview]
Message-ID: <20170214183807.GT6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <874lzwlmch.fsf@ashishki-desk.ger.corp.intel.com>
On Tue, Feb 14, 2017 at 07:21:34PM +0200, Alexander Shishkin wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
>
> > On Tue, Feb 14, 2017 at 06:17:30PM +0200, Alexander Shishkin wrote:
> >> This is called by pmu::add(), which checks hw.state afterwards and if it
> >> finds HES_STOPPED, it returns an error, which event_sched_in() captures
> >> and keeps the event in INACTIVE state. Should I add a comment about it?
> >
> > Egads... so what if ->add() succeeds but we then hit this on
> > ->stop()/->start() due to throttle or period adjust?
>
> It will hang there with hw.state==PERF_HES_STOPPED till the next
> sched_out. But that will be the case anyway if VMXON kicks in while PT
> is running.
Right, so I question the whole 'lets not schedule PT when VMX' premise,
it leads to inconsistencies all over. How about we treat it like
->add() succeeded and VMX simply results in no output.
Esp. when you then emit 'fake' data into/from a vmlaunch/vmresume
instruction.
next prev parent reply other threads:[~2017-02-14 18:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 13:24 [PATCH 0/2] perf/x86/intel/pt: VMX related updates Alexander Shishkin
2017-02-14 13:24 ` [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin
2017-02-14 13:56 ` Peter Zijlstra
2017-02-14 16:17 ` Alexander Shishkin
2017-02-14 16:27 ` Peter Zijlstra
2017-02-14 17:21 ` Alexander Shishkin
2017-02-14 18:38 ` Peter Zijlstra [this message]
2017-02-14 19:48 ` Peter Zijlstra
2017-02-15 8:11 ` Alexander Shishkin
2017-02-15 8:53 ` Peter Zijlstra
2017-02-14 13:24 ` [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin
2017-02-14 14:02 ` Peter Zijlstra
2017-02-14 17:47 ` Arnaldo Carvalho de Melo
2017-02-15 8:34 ` Alexander Shishkin
2017-02-15 8:56 ` Peter Zijlstra
2017-02-15 13:05 ` Alexander Shishkin
2017-02-15 13:12 ` Arnaldo Carvalho de Melo
2017-02-15 13:37 ` Peter Zijlstra
2017-02-15 12:51 ` Arnaldo Carvalho de Melo
2017-02-15 13:09 ` Alexander Shishkin
2017-02-15 13:16 ` Arnaldo Carvalho de Melo
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