Re: About using PEBS from the user space

[Manuel Selva <selva.manuel@gmail.com>]

Hello Harald,

Setting the  config1 field of the perf_event_attr field (as done by the 
perf mem record tool) to X will instruct the PMU to only sample loads 
with latency higher than X. Is it what you are looking for ?

----
Manu

On 06/25/2015 06:00 PM, Harald Servat wrote:
> 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!
>
> WARNING / LEGAL TEXT: This message is intended only for the use of the
> individual or entity to which it is addressed and may contain
> information which is privileged, confidential, proprietary, or exempt
> from disclosure under applicable law. If you are not the intended
> recipient or the person responsible for delivering the message to the
> intended recipient, you are strictly prohibited from disclosing,
> distributing, copying, or in any way using this message. If you have
> received this communication in error, please notify the sender and
> destroy and delete any copies you may have received.
>
> http://www.bsc.es/disclaimer
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-perf-users" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>