Re: [PATCH 1/6] perf, x86: Basic Haswell LBR call stack support

From: Stephane Eranian
Date: Tue Oct 23 2012 - 08:08:59 EST


On Tue, Oct 23, 2012 at 7:41 AM, Yan, Zheng <zheng.z.yan@xxxxxxxxx> wrote:
> On 10/22/2012 06:35 PM, Peter Zijlstra wrote:
>> On Mon, 2012-10-22 at 14:11 +0800, Yan, Zheng wrote:
>>> --- a/include/uapi/linux/perf_event.h
>>> +++ b/include/uapi/linux/perf_event.h
>>> @@ -160,8 +160,9 @@ enum perf_branch_sample_type {
>>> PERF_SAMPLE_BRANCH_ABORT = 1U << 7, /* transaction aborts */
>>> PERF_SAMPLE_BRANCH_INTX = 1U << 8, /* in transaction (flag) */
>>> PERF_SAMPLE_BRANCH_NOTX = 1U << 9, /* not in transaction (flag) */
>>> + PERF_SAMPLE_BRANCH_CALL_STACK = 1U << 10, /* call stack */
>>>
>>> - PERF_SAMPLE_BRANCH_MAX = 1U << 10, /* non-ABI */
>>> + PERF_SAMPLE_BRANCH_MAX = 1U << 11, /* non-ABI */
>>> };
>>
>> You add an ABI sample type without mentioning it in your changelog.. I
>> think I'll stop reading here.
>>
> Ok, I will add the ABI change to the change log. Do you think we should hide this
> branch sample type from user?
>
Certainly not. what's the point of this?
Unless, it is so broken that it does not work at all.

> Regards
> Yan, Zheng
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