linux-kernel - Re: [PATCH 1/2] perf: Add more generic branch types

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Message-ID: <e9c4eab7-51b4-6794-0d02-2d325c300e33@arm.com>
Date:   Thu, 24 Feb 2022 11:21:32 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, robh@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH 1/2] perf: Add more generic branch types



On 2/2/22 5:28 PM, Mark Rutland wrote:
> Hi Anshuman,
> 
> On Fri, Jan 28, 2022 at 11:14:12AM +0530, Anshuman Khandual wrote:
>> This expands generic branch type classification by adding some more entries
>> , that can still be represented with the existing 4 bit 'type' field. While
>> here this also updates the x86 implementation with these new branch types.
> It looks like there's some whitespace damage here.
> 
>>>From a quick scan of the below, I think the "exception return" and "IRQ
> exception" types are somewhat generic, and could be added now (aside from any
> bikeshedding over names), but:

Hi Mark,

I have sent a patch adding just PERF_BR_ERET and PERF_BR_IRQ which are generic
enough to be included now. The 'type' field still got 3 more places for future
use. Hence we should try and include two more branch types, before adding the
last entry for ABI expansion (e.g PERF_BR_EXTENDED).

https://lore.kernel.org/all/1645681014-3346-1-git-send-email-anshuman.khandual@arm.com/

- Anshuman