From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 22 Dec 2008 10:10:42 +0000 (+0100)
Subject: x86, perfcounters: add support for fixed-function pmcs
X-Git-Tag: v2.6.31-rc1~383^2~538
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f18d1e8d07ae67dd0afce875287756d4bd31a46;p=pandora-kernel.git

x86, perfcounters: add support for fixed-function pmcs

Impact: extend performance counter support on x86 Intel CPUs

Modern Intel CPUs have 3 "fixed-function" performance counters, which
count these hardware events:

    Instr_Retired.Any
    CPU_CLK_Unhalted.Core
    CPU_CLK_Unhalted.Ref

Add support for them to the performance counters subsystem.

Their use is transparent to user-space: the counter scheduler is
extended to automatically recognize the cases where a fixed-function
PMC can be utilized instead of a generic PMC. In such cases the
generic PMC is kept available for more counters.

The above fixed-function events map to these generic counter hw events:

        PERF_COUNT_INSTRUCTIONS
        PERF_COUNT_CPU_CYCLES
        PERF_COUNT_BUS_CYCLES

(The 'bus' cycles are in reality often CPU-ish cycles, just with a fixed
 frequency.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
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