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X-CSE-ConnectionGUID: AF0BHQCwTFui3UGn9qLekw== X-CSE-MsgGUID: u9oRi0g4S7u211CUCL0jcg== X-IronPort-AV: E=McAfee;i="6800,10657,11919"; a="93812361" X-IronPort-AV: E=Sophos;i="6.27,128,1787036400"; d="scan'208";a="93812361" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 10:22:20 -0700 X-CSE-ConnectionGUID: S/3A8+pYSMabJE62UZpwYA== X-CSE-MsgGUID: poEqxYK2T+iIpz01g3ziGw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,128,1787036400"; d="scan'208";a="279831713" Received: from schen9-mobl4.amr.corp.intel.com (HELO [10.125.111.82]) ([10.125.111.82]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 10:22:19 -0700 Message-ID: <2e64c909e48087b188b8220344ef6576bd273373.camel@linux.intel.com> Subject: Re: Cache-aware scheduling does not work well with amd big/little cores From: Tim Chen To: Klaus Kusche , Chen Yu Cc: Mario Limonciello , "Badole, Vishal" , Peter Zijlstra , linux-kernel@vger.kernel.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , platform-driver-x86@vger.kernel.org, K Prateek Nayak , ricardo.neri@intel.com Date: Mon, 28 Sep 2026 10:22:02 -0700 In-Reply-To: References: <369d0bbb-db7a-4f86-bee2-332d5295c452@computerix.info> <406a5c407bbe60cafc24f715e089f5552a0791f9.camel@linux.intel.com> <14630984-9287-4454-b52f-3a1e526e1fdf@computerix.info> <3cb5cbdb227bee0b822f1550e10659faadd77a3d.camel@linux.intel.com> <76dba935-1052-4fa9-a70c-16cecdfd12c8@amd.com> <4da55124e32dd0587a3516c8f5ed512bffbbb42e.camel@linux.intel.com> <2fe2c681-b748-41fa-8b56-1169c86cefbc@intel.com> <6b173ff1-6fde-401d-a4a8-6fa8bbe3287c@computerix.info> <8aea0f25-0317-42ac-b59f-1a008c6eb106@computerix.info> <7b83cf0cd1704b552978af88d7de9c57970c23a1.camel@linux.intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.1 (3.58.1-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sun, 2026-09-27 at 12:47 +0200, Klaus Kusche wrote: > Hello, >=20 > this one looks good. > It does not show any core assignment anomalies=20 > in the core bar graph (i.e. no processes are staying=20 > on little cores when big cores are idle), > and at least for the two compile jobs I tested, > it gives timings which are=20 >=20 > * better w.r.t. elapsed wallclock time > (sometimes slightly, sometimes significantly) > than all other versions and patches I tried so far > with cache-aware scheduling on >=20 > * and at least as good as the unpatched kernel > with cache-aware scheduling turned off > (so one does not loose anything by turning it on). Thank you for testing and sharing the results so quickly. I will send a cleaned up patch for sched/urgent branch shortly for Peter. Tim >=20 > As expected, the uv build profits more than the kernel built, > because besides all-cores-loaded and single-core-loaded phases, > it spends significant time with about half as many busy processes > as cores, and in these phases, placement makes a difference. >=20 > Klaus Kusche >=20