Messages in this thread | | | Date | Mon, 22 Jun 2009 22:26:15 +0200 | Subject | perf_counter Atom patch | From | stephane eranian <> |
| |
Hi,
You recently submitted a patch for perf_counter to disable use of fixed counters on Atom because you claim they do not work.
-------------------------------------------------------------------------------------- author Yong Wang <yong.y.wang@linux.intel.com> Fri, 12 Jun 2009 08:08:55 +0000 (16:08 +0800) committer Ingo Molnar <mingo@elte.hu> Fri, 12 Jun 2009 11:48:32 +0000 (13:48 +0200) commit dff5da6d09daaab40a8741dce0ed3c2e94079de2 tree c1f4ce70e4a566a231ba00c775de4e96fb8acb39 parent faafec1e61e61d350248af2a7e5f047606adab6e perf_counter/x86: Add a quirk for Atom processors
The fixed-function performance counters do not work on current Atom processors. Use the general-purpose ones instead. --------------------------------------------------------------------------------------
I would like to better understand what makes you think this is the case.
Perfmon is working on Atom and there, fixed counters work perfectly: $ head -6 /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 28 model name : Intel(R) Atom(TM) CPU 230 @ 1.60GHz stepping : 2 ... $ pfmon -v --us-c -e unhalted_core_cycles,unhalted_reference_cycles,instructions_retired noploop 10 [FIXED_CTRL(pmc16)=0xaaa pmi0=1 en0=0x2 any0=0 pmi1=1 en1=0x2 any1=0 pmi2=1 en2=0x2 any2=0] INSTRUCTIONS_RETIRED UNHALTED_CORE_CYCLES UNHALTED_REFERENCE_CYCLES [FIXED_CTR0(pmd16)] [FIXED_CTR1(pmd17)] [FIXED_CTR2(pmd18)] noploop for 10 seconds 15,902,604,169 UNHALTED_CORE_CYCLES 15,902,586,180 UNHALTED_REFERENCE_CYCLES 7,941,842,505 INSTRUCTIONS_RETIRED
I seem to recall that what may be bogus on Atom is what is returned by CPUID(0xa) for the fixed counters. But they are there and they work. Thus, I believe, the quirk should be at the location where CPUID(0xa) is invoked not where you've put it.
| |