From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f171.google.com (mail-lj1-f171.google.com [209.85.208.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F22BF1855 for ; Fri, 1 Jul 2022 10:18:07 +0000 (UTC) Received: by mail-lj1-f171.google.com with SMTP id s14so2068580ljs.3 for ; Fri, 01 Jul 2022 03:18:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cIolBCU7gcHiWTJ7Gpz8DTqiA6rqBEHvQmHzGRqousg=; b=Tsu50rHkMeDdYBlop1NXOkXacqld+/mROcbAkLLL9IKpVpS0O3IMeEC6FDNB9QY+Cp cpVOpFWBaz9xIVZjtXFyQBP4RcWq7dtN/dMivs5vyH0EiZItaddL0DTr+mlDqx4HRBcV gjNgyNT2mAKgIRG+ywfq4XeeqVHO4HGodUM5fPjc0rEaFB+Kw5XeQsMbbNuuC/4kLguA eRrc6ZZkUt6ZCDHu/b/5XUr9OJalXfaYStCIapCM2GkCXVxYKUu/sJKlGg7o18UvQQXh EKVzTOymN4rDUGUQPsqDOljADJSq9ZN3tOlLt3W4YJxchaCvp38lp+XkUv/tTuYyhrsw XGyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cIolBCU7gcHiWTJ7Gpz8DTqiA6rqBEHvQmHzGRqousg=; b=cFlv91sdAp5lKkQMVExIMg/09uc4vycAVuGugP4IiBdcGEXgtGuccUkFg6Qwl/5PGx jAdP0lIkVZ8EMkn825jYL+HaYd7VCApxRbh5E/BwL5x/7DHld6QxDihwRhu5DIKxU2KK lDBBt3HldVRgrdrUdKDuEWI3ORHOryO78pUxy3gcpDdkNiXsT+XmLHo0j94MN+q5Fhtp MSlpzl5VM8OoiTzEkGddJxeJ0Arpa8JNXHeAlPH9HwsoMYnduiC5RpV+UpSh6hP/FABu u5NViXfGhALhfgagKKbDieQ7O8gHDENYG6RyVhPmRCtjkeh63mTmXxQRuD1evyyjIAsE QedQ== X-Gm-Message-State: AJIora8FAbWN9pBhF+67McOkpGnG31lHoyXLqJMN7qYLTWlFYbR9Sh8T FjOGcSMXftVRS+zoUjrjMV8JrJP5lK275beS1VU1 X-Google-Smtp-Source: AGRyM1t3lOfOZoHXwVnMDWhboz8bguGORAaLuR/2mXXUBqIljjrfUi+TFS8tmnoskTXPHfF5tw9dISFc3NVLOay3d08= X-Received: by 2002:a2e:8794:0:b0:25a:69cc:382d with SMTP id n20-20020a2e8794000000b0025a69cc382dmr7582956lji.424.1656670685813; Fri, 01 Jul 2022 03:18:05 -0700 (PDT) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <87mtf7z0rt.fsf@gnu.org> <6F9E9D93-3913-4022-9384-D809C8EF7715@oracle.com> <878rpgpvfj.fsf@gnu.org> In-Reply-To: From: Bill Wendling Date: Fri, 1 Jul 2022 03:17:54 -0700 Message-ID: Subject: Re: plumbers session on profiling? To: Peter Zijlstra Cc: "Jose E. Marchesi" , Ruud van der Pas , Nick Desaulniers , Sami Tolvanen , Vladimir Mezentsev , clang-built-linux , LKML , Yonghong Song , Wenlei He , Hongtao Yu , Ingo Molnar , linux-toolchains , elena.zannoni@oracle.com Content-Type: text/plain; charset="UTF-8" On Fri, Jul 1, 2022 at 2:02 AM Peter Zijlstra wrote: > > On Tue, Jun 28, 2022 at 07:08:48PM +0200, Jose E. Marchesi wrote: > > > > [Added linux-toolchains@vger in CC] > > > > It would be interesting to have some discussion in the Toolchains track > > on building the kernel with PGO/FDO. I have seen a raise on interest on > > the topic in several companies, but it would make very little sense if > > no kernel hacker is interested in participating... anybody? > > I know there's been a lot of work in this area, but none of it seems to > have trickled down to be easy enough for me to use it. We use an instrumented kernel to collect the data we need. It gives us the best payoff, because the profiling data is more fine-grained and accurate. (PGO does much more than make inlining decisions.) If I recall correctly, you previously suggested using sampling data. (Correct?) Is there a document or article that outlines that process? -bw