linux-kernel - Re: [tip:perf/core] perf/x86/intel: Disable userspace RDPMC usage for large PEBS

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Message-ID: <c3880b40-3f45-9820-a7af-6b87b23899ae@linux.intel.com>
Date:   Fri, 9 Mar 2018 13:53:55 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Vince Weaver <vincent.weaver@...ne.edu>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        torvalds@...ux-foundation.org, eranian@...gle.com, acme@...hat.com,
        hpa@...or.com, alexander.shishkin@...ux.intel.com,
        mingo@...nel.org, jolsa@...hat.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] perf/x86/intel: Disable userspace RDPMC usage for
 large PEBS



On 3/9/2018 12:42 PM, Peter Zijlstra wrote:
> On Fri, Mar 09, 2018 at 09:31:11AM -0500, Vince Weaver wrote:
>> On Fri, 9 Mar 2018, tip-bot for Kan Liang wrote:
>>
>>> Commit-ID:  1af22eba248efe2de25658041a80a3d40fb3e92e
>>> Gitweb:     https://git.kernel.org/tip/1af22eba248efe2de25658041a80a3d40fb3e92e
>>> Author:     Kan Liang <kan.liang@...ux.intel.com>
>>> AuthorDate: Mon, 12 Feb 2018 14:20:35 -0800
>>> Committer:  Ingo Molnar <mingo@...nel.org>
>>> CommitDate: Fri, 9 Mar 2018 08:22:23 +0100
>>>
>>> perf/x86/intel: Disable userspace RDPMC usage for large PEBS
>>>
>>
>>
>> So this whole commit log is about disabling RDPMC usage for "large PEBS"
>> but the actual change disables RDPMC if "PERF_X86_EVENT_FREERUNNING"
>>
>> Either the commit log is really misleading, or else a poor name was chosen
>> for this feature.
> 
> Its the same thing, and yes that might want renaming I suppose.
>

Yes, I will send a patch to rename the "FREERUNNING" to "LARGE_PEBS", 
and fix the confusion.

Thanks,
Kan