Re: [Xen-users] Reading hardware performance events in xen dom0

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, May 06, 2013 at 11:52:54AM +0100, Tsafack Chetsa Ghislain Landry wrote:
> Greetings,
> 
> Sorry for disturbing, I have just installed Xen on my system (kernel version 
> 2.6.32-5-xen-amd64) and I would like to read hardware events in dom0, I have 
> a program which usually do that in non-Xen kernels (see beneath).
> 
> void open_perf(struct perf_event_attr* attr) {
>   static int current=0;
>   int cpu;
>   for(cpu=0; cpu<NBCORE; cpu++) {
>     perfctr[current+cpu]=sys_perf_event_open(attr, -1, cpu, -1, 0);
> 
>     if(perfctr[current+cpu] <0) {
>       printf("open : %d (%d et %d)\n", perfctr[current+cpu], attr->config, 
> current+cpu);
>       exit(1);
>     }
>   }
>   current+=NBCORE;
> }
> 
> The problem is that the system call "sys_perf_event_open" systematically 
> returns -1
> 
> I was wondering whether anyone has experienced the same issue and how I get 
> rid of that.
> 
> I tried using perf, but I guess the same thing happens:
> here is an example:
> 
> Performance counter stats for 'mpirun -np 2 ./ep.A':
> 
>    55075.066063  task-clock-msecs         #      1.986 CPUs
>             282  context-switches         #      0.000 M/sec
>               4  CPU-migrations           #      0.000 M/sec
>            2330  page-faults              #      0.000 M/sec
>   <not counted>  cycles
>   <not counted>  instructions
>   <not counted>  cache-references
>   <not counted>  cache-misses
> 
>    27.735049988  seconds time elapsed
> 

AFAICT this is not yet supported. Boris@oracle seems to be working on
getting perf to profile Dom0 and Xen.


Wei.

> --
> Landry

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> Xen-users@xxxxxxxxxxxxx
> http://lists.xen.org/xen-users


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