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

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Message-ID: <08f9f344-4414-4819-87b9-538d8ed3b040@linux.intel.com>
Date: Thu, 27 Feb 2025 10:05:50 +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 5:46 PM, Peter Zijlstra wrote:
> On Wed, Feb 26, 2025 at 01:48:52PM +0800, Mi, Dapeng wrote:
>> On 2/25/2025 7:18 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.
>>> Not loving how this patch obscures the whole DS area thing and naming.
>> arch-PEBS uses a totally independent buffer to save the PEBS records and
>> don't use the debug store area anymore. To reuse the original function as
>> much as possible and don't mislead users to think arch-PEBS has some
>> relationship with debug store, the original key word "ds" in the function
>> names are changed to "BTS_PEBS". I know the name maybe not perfect, do you
>> have any suggestion? Thanks.
> Right, so I realize it has a new buffer, but why do you need to make it
> all complicated like this?
>
> Just leave the existing stuff and stick the new arch pebs buffer
> somewhere new. All that reserve nonsense shouldn't be needed anymore.
>
> Just add it to the intel_pmu_cpu_{prepare,starting,dying,dead} things.

Sure. would do.