From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Robert Richter <rric@kernel.org>, Josh Boyer <jwboyer@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
x86@kernel.org, linux-kernel@vger.kernel.org, gleb@redhat.com
Subject: Re: Drop WARN on AMD lack of perfctrs
Date: Fri, 17 May 2013 11:27:41 +0200 [thread overview]
Message-ID: <20130517092741.GR19669@dyad.programming.kicks-ass.net> (raw)
In-Reply-To: <20130517091651.GB23035@pd.tnic>
On Fri, May 17, 2013 at 11:16:51AM +0200, Borislav Petkov wrote:
> On Fri, May 17, 2013 at 11:04:51AM +0200, Peter Zijlstra wrote:
> > Mostly so that check_hw_exists() doesn't need to know about the vendor
> > specifics like where the MSRs live, how many there are etc..
>
> Yep, but there will still be issues with perf when booted on a guest and
> kvm not supporting it. And AFAIU, they're signalling this by turning off
> CPUID bits so that initializing perf doesn't happen.
>
> So, I think init_hw_perf_events should as a first step look at CPUID
> bits and then do anything else. And this is done on Intel with
> X86_FEATURE_ARCH_PERFMON. But Robert is fixing this on AMD too so...
But not all x86 hardware even has the stuff enumerated in CPUID, and afaict
Intel and AMD use a different CPUID bit as well, so what's
init_hw_perf_events() to do?
next prev parent reply other threads:[~2013-05-17 9:29 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-16 15:10 Drop WARN on AMD lack of perfctrs Josh Boyer
2013-05-16 17:51 ` Peter Zijlstra
2013-05-16 17:55 ` Josh Boyer
2013-05-16 18:10 ` Peter Zijlstra
2013-05-16 20:55 ` Robert Richter
2013-05-16 21:34 ` Borislav Petkov
2013-05-17 9:04 ` Peter Zijlstra
2013-05-17 9:16 ` Borislav Petkov
2013-05-17 9:27 ` Peter Zijlstra [this message]
2013-05-17 9:45 ` Borislav Petkov
2013-05-17 10:36 ` Robert Richter
2013-05-17 10:57 ` Peter Zijlstra
2013-05-21 8:56 ` Robert Richter
2013-05-21 11:05 ` Peter Zijlstra
2013-05-21 13:58 ` Robert Richter
2013-05-21 15:20 ` Jacob Shin
2013-05-28 13:03 ` [tip:perf/core] perf/x86/amd: Rework AMD PMU init code tip-bot for Peter Zijlstra
2013-05-16 21:54 ` Drop WARN on AMD lack of perfctrs Josh Boyer
2013-05-16 22:33 ` Robert Richter
2013-05-16 19:31 ` Gleb Natapov
2013-05-16 20:00 ` Borislav Petkov
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