From: Peter Zijlstra <peterz@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>,
linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: perf: multiple mmap of fd behavior on x86/ARM
Date: Fri, 11 Aug 2017 12:52:52 +0200 [thread overview]
Message-ID: <20170811105252.zuaihhfyvvpvm3uz@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20170811100127.GB12985@leverpostej>
On Fri, Aug 11, 2017 at 11:01:27AM +0100, Mark Rutland wrote:
> On Thu, Aug 10, 2017 at 02:48:52PM -0400, Vince Weaver wrote:
> >
> > So I was working on my perf_event_tests on ARM/ARM64 (the end goal was to
> > get ARM64 rdpmc support working, but apparently those patches never made
> > it upstream?)
>
> IIUC by 'rdpmc' you mean direct userspace counter access?
>
> Patches for that never made it upstream. Last I saw, there were no
> patches in a suitable state for review.
>
> There are also difficulties (e.g. big.LITTLE systems where the number of
> counters can differ across CPUs) which have yet to be solved.
How would that be a problem? The API gives an explicit index to use with
the 'rdpmc' instruction.
next prev parent reply other threads:[~2017-08-11 10:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-10 18:48 perf: multiple mmap of fd behavior on x86/ARM Vince Weaver
2017-08-11 10:01 ` Mark Rutland
2017-08-11 10:52 ` Peter Zijlstra [this message]
2017-08-11 11:06 ` Mark Rutland
2017-08-11 14:53 ` Peter Zijlstra
2017-08-14 10:57 ` Will Deacon
2017-08-11 15:25 ` Vince Weaver
2017-08-11 16:23 ` Mark Rutland
2017-08-11 16:51 ` Vince Weaver
2017-08-11 17:09 ` Mark Rutland
2017-08-11 19:01 ` Vince Weaver
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