mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Puranjay Mohan <puranjay@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>,
	<linux-perf-users@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	James Clark <james.clark@linaro.org>,
	"Thomas Gleixner" <tglx@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [PATCH RFC] perf/x86/amd/lbr: Don't freeze the LBR on PMI for user-only filters
Date: Thu, 12 Nov 2026 16:39:23 +0530	[thread overview]
Message-ID: <3b28aa06-1496-42b1-b1d2-c654c7a1ff0c@amd.com> (raw)
In-Reply-To: <CAEf4BzaGnsOhpz=bOxoSEyy-8W0epd5Go6juimoqDge+Rc-+Dw@mail.gmail.com>

Puranjay, Andrii,

>> heh, so we basically either
>>
>> a) opt-in freeze with *new config*, but do it *only for non-kernel LBR*
>>
>> or
>>
>> b) opt-out freeze *only for non-kernel LBR* _unconditionally_, but
>> without adding any new config
>>
>> In both cases we have a behavior that makes sense in practice, but a)
>> adds some new config, while b) doesn't add anything. End result is the
>> same, just more configuration and need to change user space code to
>> opt-out the freeze.
>>
>> Is a) worth it, or we should stick to b) and keep it simple, Sandipan?

Have you run a PGO experiment with the patch, and does it show a
benefit? Also, have you seen any regression in any benchmarks? If
no-freeze regresses some of them, we may need to give the user an
option to keep the freeze enabled. No?

Thanks,
Ravi

      reply	other threads:[~2026-11-12 11:09 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-23 12:41 [PATCH] perf/x86/amd/lbr: Freeze LBR on PMI only when kernel branches are recorded Puranjay Mohan
2026-10-26 15:35 ` Sandipan Das
2026-10-29 20:12 ` Andrii Nakryiko
2026-11-02 10:08   ` Sandipan Das
2026-11-03 19:09     ` Andrii Nakryiko
2026-11-05  6:17       ` Sandipan Das
2026-11-05 16:58         ` Andrii Nakryiko
2026-11-05 17:03         ` [PATCH RFC] perf/x86/amd/lbr: Don't freeze the LBR on PMI for user-only filters Puranjay Mohan
2026-11-06  1:07           ` Andrii Nakryiko
2026-11-10 19:05             ` Andrii Nakryiko
2026-11-12 11:09               ` Ravi Bangoria [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=3b28aa06-1496-42b1-b1d2-c654c7a1ff0c@amd.com \
    --to=ravi.bangoria@amd.com \
    --cc=acme@kernel.org \
    --cc=adrian.hunter@intel.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=andrii.nakryiko@gmail.com \
    --cc=andrii@kernel.org \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=irogers@google.com \
    --cc=james.clark@linaro.org \
    --cc=jolsa@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-perf-users@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=puranjay@kernel.org \
    --cc=sandipan.das@amd.com \
    --cc=tglx@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®