Re: operf taking 100% cpu

On 01/27/2015 06:51 PM, Xin Tong wrote:
> ​what does perf do ? is it a different tool from operf ? the perf command generates perf.data and i do not need to tell it what performance counters i want to collect ?
> 
> bash-4.1$ perf record --pid=44637
>    755 root      39  19     0    0    0 R 100.0  0.0  14085:51 kipmi0
>  44637 xintong1  20   0  3928  344  268 R 100.0  0.0   0:37.75 loop

Hi Xin,

perf is a tools that is included in the kernel source that also uses the performance monitoring hardware like operf. Most newer linux distributions also package the perf executables in a package.  By default it uses cycles as the thing sampling metric.  Assuming that you have perf installed on the machine you can do record some data with the following (hit cntl-c to stop data recording)

$ perf record --pid=44637

This will record data in perf.data in the directory.  The use the following to look at the data

$ perf report

The following URL has more information about perf:

http://web.eece.maine.edu/~vweaver/projects/perf_events/

-Will

> 
> 
> ​
> 
> On Tue, Jan 27, 2015 at 8:44 AM, William Cohen <[email protected] <mailto:[email protected]>> wrote:
> 
>     On 01/27/2015 08:31 AM, Maucci, Cyrille wrote:
>     > Did you try ‘perf top’ on operf ? J
> 
>     "perf top" will require root privileges. Alternatively,  as a normal users you could use:
> 
>     - "perf record --pid=<monitored_operf_pid>"
>     - in a different directory to avoid overwiting the data you could use another operf with the --pid=<monitored_operf_pid>
> 
>     Xin, could you post the results on this mailing lis?.  It would be good to eliminate this issue from operf.
> 
>     -Will
>     >
>     >
>     >
>     > *From:*Xin Tong [mailto:[email protected] <mailto:[email protected]>]
>     > *Sent:* Friday, January 23, 2015 12:57 AM
>     > *To:* [email protected] <mailto:[email protected]>
>     > *Subject:* operf taking 100% cpu
>     >
>     >
>     >
>     > I am running oprofile on a linux intel haswell machine. and the operf process is taking close to 100% of the time. what is operf doing with that amount of cpu cycles ? maybe its polling on something ? how do i fix this ?
>     >
>     >
>     >
>     > operf --separate-thread --event=CPU_CLK_UNHALTED:10000000 ./gcc/bin/viterb00data_2.exe -autogo && opreport  -l -g -d --xml -o current.opm
>     >
>     >
>     >
>     > top - 15:56:34 up 69 days,  2:59, 13 users,  load average: 2.04, 1.71, 1.43
>     >
>     > Tasks: 1196 total,   4 running, 1191 sleeping,   1 stopped,   0 zombie
>     >
>     > Cpu(s):  1.1%us,  0.1%sy,  0.0%ni, 98.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
>     >
>     > Mem:  60853364k total, 39834668k used, 21018696k free,   818524k buffers
>     >
>     > Swap: 20479992k total,     1428k used, 20478564k free, 34594044k cached
>     >
>     >
>     >
>     >    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>     >
>     >    755 root      39  19     0    0    0 R 98.3  0.0   6891:01 kipmi0
>     >
>     > 118201 xintong1  20   0 14448 1700 1412 R 98.3  0.0   0:03.06 operf
>     >
>     > 118206 xintong1  20   0 15020  660  524 R 98.3  0.0   0:03.06 viterb00data_2.
>     >
>     >
>     >
>     >
>     >
>     > Thanks,
>     >
>     > Xin
>     >
>     >
>     >
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> 
> 


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