linux-kernel - Re: [Patch v2 12/24] perf/x86/intel: Allocate arch-PEBS buffer and initialize PEBS

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Message-ID: <5bce57a6-f554-4a54-bf87-08a30c60bea9@linux.intel.com>
Date: Thu, 27 Feb 2025 10:09:01 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo
 <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
 Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Kan Liang <kan.liang@...ux.intel.com>, Andi Kleen <ak@...ux.intel.com>,
 Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [Patch v2 12/24] perf/x86/intel: Allocate arch-PEBS buffer and
 initialize PEBS_BASE MSR


On 2/26/2025 5:48 PM, Peter Zijlstra wrote:
> On Wed, Feb 26, 2025 at 02:19:15PM +0800, Mi, Dapeng wrote:
>> On 2/25/2025 7:25 PM, Peter Zijlstra wrote:
>>> On Tue, Feb 18, 2025 at 03:28:06PM +0000, Dapeng Mi wrote:
>>>> Arch-PEBS introduces a new MSR IA32_PEBS_BASE to store the arch-PEBS
>>>> buffer physical address. This patch allocates arch-PEBS buffer and then
>>>> initialize IA32_PEBS_BASE MSR with the buffer physical address.
>>> Just to clarify, parts with ARCH PEBS will not have BTS and thus not
>>> have DS?
>> No, DS and BTS still exist along with arch-PEBS, only the legacy DS based
>> PEBS is unavailable and replaced by arch-PEBS.
> Joy. Is anybody still using BTS now that we have PT? I thought PT was
> supposed to be the better BTS.

Yeah, I suppose no one still use BTS, but suppose it would need a long time
to drop BTS on HW.