* perf branch
@ 2014-04-14 3:55 Noah Luther
2014-04-14 12:53 ` Christopher Covington
2014-04-14 17:41 ` Andi Kleen
0 siblings, 2 replies; 3+ messages in thread
From: Noah Luther @ 2014-04-14 3:55 UTC (permalink / raw)
To: linux-perf-users
Hello,
I am trying to use perf to trace branches as described by the 'perf
branch' subcommand. Is there support through perf_event_open to access
the buffer storing branch traces? I saw Akihiro Nagai's presentation
on 'perf branch', but haven't yet figured out how to enable BTS and
access the buffer based on the documentation on this page:
http://web.eece.maine.edu/~vweaver/projects/perf_events/perf_event_open.html
If there are any resources that might be of use to me, I would
appreciate any assistance.
Thank you,
Noah
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: perf branch
2014-04-14 3:55 perf branch Noah Luther
@ 2014-04-14 12:53 ` Christopher Covington
2014-04-14 17:41 ` Andi Kleen
1 sibling, 0 replies; 3+ messages in thread
From: Christopher Covington @ 2014-04-14 12:53 UTC (permalink / raw)
To: Noah Luther; +Cc: linux-perf-users
Hi Noah,
On 04/13/2014 11:55 PM, Noah Luther wrote:
> Hello,
>
> I am trying to use perf to trace branches as described by the 'perf
> branch' subcommand. Is there support through perf_event_open to access
> the buffer storing branch traces? I saw Akihiro Nagai's presentation
> on 'perf branch', but haven't yet figured out how to enable BTS and
> access the buffer based on the documentation on this page:
>
> http://web.eece.maine.edu/~vweaver/projects/perf_events/perf_event_open.html
>
> If there are any resources that might be of use to me, I would
> appreciate any assistance.
In the past I've found the test suite to be a useful reference. Here's a test
that looks like it might serve as a jumping-off point.
https://github.com/deater/perf_event_tests/blob/master/tests/record_sample/sample_branch_stack.c
Regards,
Christopher
--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: perf branch
2014-04-14 3:55 perf branch Noah Luther
2014-04-14 12:53 ` Christopher Covington
@ 2014-04-14 17:41 ` Andi Kleen
1 sibling, 0 replies; 3+ messages in thread
From: Andi Kleen @ 2014-04-14 17:41 UTC (permalink / raw)
To: Noah Luther; +Cc: linux-perf-users
Noah Luther <nluther@vt.edu> writes:
> Hello,
>
> I am trying to use perf to trace branches as described by the 'perf
> branch' subcommand. Is there support through perf_event_open to access
> the buffer storing branch traces? I saw Akihiro Nagai's presentation
> on 'perf branch', but haven't yet figured out how to enable BTS and
> access the buffer based on the documentation on this page:
>
> http://web.eece.maine.edu/~vweaver/projects/perf_events/perf_event_open.html
>
> If there are any resources that might be of use to me, I would
> appreciate any assistance.
perf branch never made it, but you can use
perf record -e branches:u -c1 ...
perf script
Also the latest GDB snapshots have builtin support for BTS through
perf in a somewhat more convenient interface.
Keep in mind that BTS is quite slow and often cannot keep up.
In the future ProcessorTrace will be better.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
^ permalink raw reply [flat|nested] 3+ messages in thread
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2014-04-14 3:55 perf branch Noah Luther
2014-04-14 12:53 ` Christopher Covington
2014-04-14 17:41 ` Andi Kleen
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