lkml.org 
[lkml]   [2009]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRE: perf_counter Atom patch
> 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?


\
 
 \ /
  Last update: 2009-06-23 08:03    [W:0.057 / U:3.840 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site