From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Stephane Eranian <eranian@google.com>,
linux-kernel@vger.kernel.org, acme@infradead.org,
robert.richter@amd.com, ming.m.lin@intel.com,
andi@firstfloor.org, asharma@fb.com
Subject: Re: [PATCH 2/4] perf_event: add PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event
Date: Sun, 11 Dec 2011 13:55:31 +0100 [thread overview]
Message-ID: <1323608131.16764.19.camel@twins> (raw)
In-Reply-To: <20111211080138.GB20790@elte.hu>
On Sun, 2011-12-11 at 09:01 +0100, Ingo Molnar wrote:
> > + PERF_COUNT_HW_REF_CPU_CYCLES = 9,
>
> Btw., that was what 'bus cycles' tried to do a long time ago:
> the constant, non-variable baseline heartbeat of the system.
This isn't about that. Its about exposing the third fixed purpose
counter. Intel, in their infinite wisdom, created a fixed purpose
counter for which there is no equivalent in the general purpose events.
Our fixed purpose counter support is predicated on the assumption that
there is, and simply maps any event code to also include the fixed
purpose counter if appropriate.
There not being an event to map from has thus far avoided exposing this
third fixed purpose event.
The problem with remapping BUS_CYCLES is that BUS_CYCLES (now) is
something you can program on the {2,4,8} general purpose counters,
whereas this new thing can only ever be ran from the 1 fixed purpose
counter.
next prev parent reply other threads:[~2011-12-11 12:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-10 23:28 [PATCH 0/4] perf_events: add support for Intel reference cycles event Stephane Eranian
2011-12-10 23:28 ` [PATCH 1/4] perf_events: enable raw event support for Intel unhalted_reference_cycles event Stephane Eranian
2011-12-21 10:22 ` [tip:perf/core] perf events: Enable " tip-bot for Stephane Eranian
2011-12-10 23:28 ` [PATCH 2/4] perf_event: add PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event Stephane Eranian
2011-12-11 8:01 ` Ingo Molnar
2011-12-11 12:55 ` Peter Zijlstra [this message]
2011-12-11 15:47 ` Ingo Molnar
2011-12-12 3:45 ` Stephane Eranian
2011-12-12 12:57 ` Peter Zijlstra
2011-12-12 17:32 ` Ingo Molnar
2011-12-13 6:45 ` Stephane Eranian
2011-12-13 10:02 ` Peter Zijlstra
2011-12-14 17:42 ` Stephane Eranian
2011-12-21 10:23 ` [tip:perf/core] perf events: Add " tip-bot for Stephane Eranian
2011-12-10 23:28 ` [PATCH 3/4] perf_events: add Intel X86 mapping for PERF_COUNT_HW_REF_CPU_CYCLES Stephane Eranian
2011-12-21 10:24 ` [tip:perf/core] perf events: Add Intel x86 " tip-bot for Stephane Eranian
2011-12-10 23:28 ` [PATCH 4/4] perf: add support for PERF_HW_COUNT_REF_CPU_CYCLES Stephane Eranian
2011-12-21 10:25 ` [tip:perf/core] perf: Add " tip-bot for Stephane Eranian
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