Messages in this thread | | | From | "Wang, Yong Y" <> | Date | Tue, 23 Jun 2009 13:59:37 +0800 | Subject | RE: perf_counter Atom patch |
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> From: Wang, Yong Y > > > From: stephane eranian [mailto:eranian@googlemail.com] > > > > I would like to better understand what makes you think > > this is the case. > > > > Because I observed that the output of 'perf stat -e 0:0 -e > 0:1 -e 0:6 <cmd>' > is always like below without the quirk. > > Performance counter stats for '<cmd>': > > 0 cycles > 0 instructions > 0 bus-cycles > > > 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 > > ... > > My cpuinfo is below and the only difference I can see is 270 vs 230. > > processor : 0 > vendor_id : GenuineIntel > cpu family : 6 > model : 28 > model name : Intel(R) Atom(TM) CPU N270 @ 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 > > > > Could you pls try to revert my patch, run 'perf stat -e 0:0 > -e 0:1 -e 0:6 <cmd>' and see > whether the counters count or not? I tried pfmon on my atom > box but it always runs into > segfault. If the fixed counters work for you, I will ask Atom > hw foks here in Intel why this > is the case and revise the code accordingly. >
I just found an Atom 230 based nettop in our lab and looks like the fixed counters do not work. Below is the output on a kernel without my patch.
atom@atom-desktop:~$ head -n 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 atom@atom-desktop:~$ ./perf stat -e 0:0 -e 0:1 -e 0:6 true
Performance counter stats for 'true':
0 cycles 0 instructions 0 bus-cycles
0.004089458 seconds time elapsed.
Are you aware of any microcode update for the Atom processor you are using?
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