Re: About using PEBS from the user space

[Harald Servat <harald.servat@bsc.es>]

On 04/05/15 00:19, Vince Weaver wrote:
> On Mon, 4 May 2015, Harald Servat wrote:
>
>> Dear list,
>>
>>    I'd like to use the perf library to access PEBS so as to collect referenced
>> memory addresses from the user space. I think I've successfully setup the perf
>> structures (struct perf_event_attr) to configure the performance counters, but
>> I don't see what should I do to access to the captured memory addresses. I've
>> seen that within arch/x86/kernel/cpu/perf_event_intel_ds.c there are the
>> routines alloc_pebs_buffer, alloc_ds_buffer which seems to allocate and setup
>> the necessary buffers using kmalloc_node calls. Question is, how can replicate
>> this from the user space? And how we should connect these buffers to the PEBS
>> infrastructure using perf calls?
>
> You can try looking at the example code in my perf_event_tests code.
> 	https://github.com/deater/perf_event_tests
>
> The stuff you are looking for is probably covered in the
> 	test/record_sample/samples_data_src
> 	test/record_sample/sample_weight
> and especially the
> 	test/record_sample/sample_regs_intr
> tests, although that last one requires a fairly recent kernel to work.
>
> Vince

Hello,

   is there a way to setup PEBS to collect information from loads that 
take at least X cycles to complete using MSR_PEBS_LD_LAT_THRESHOLD 
through this approach?

Thank you!

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