From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AD737147C9D for ; Thu, 11 Apr 2024 10:38:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712831936; cv=none; b=pRueDAl2uiSa5mG0TFsyXU8k50t3w7l3Do9urAPKhQMahOv1E4a2pYOSuwlubOkqvHjfX/ijQ92m5OL1a8NfcIgv+NOHtvC8+nl/LQae0CWG2GjQYAFT97HIeC6DeBSacteVvd1fIqwg6O/0TDQpFiSl2MfM3WGLQpL5RKtemZA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712831936; c=relaxed/simple; bh=4bkwHo8HvOVpM773QtBhdjug2HdT83ARAY5I3dAxDRk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YIANaMZYHW58CuzJSQ7HjGjRkAWF/BP52aFK6FqzYZg4J1kRlgG+ZHcL6b6bwXsfzsPBGSVbbwVfaBS5+A7R0g7Ckz+URFcP88hMxYKqwo1bXTFIzN149ZBb5OeXCgb4Xd982hSoJlnFNlp7X81C7f36BB6RVUoJTiBuAeIzP0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=jAX3JCdI; arc=none smtp.client-ip=192.198.163.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="jAX3JCdI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1712831935; x=1744367935; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=4bkwHo8HvOVpM773QtBhdjug2HdT83ARAY5I3dAxDRk=; b=jAX3JCdIkToZijxGGLffAaGr36ybzmChgKZHsIO6/71jNn9Jqj35KfTf qveq6JAvOl8gfX6kLcuW3QTT8KfGYM9m905/t65Z46bhxWofs1RN63mh+ KPpISTGeumfvYCjIlDv85YKnk0A+Huxyb4Iwk55wkK31EgFQvB8cLCcbh 57tb9Ze3bNUzml3hYf61ePySt015wFptQ2LU8xpOhvzgjhLUmFilqNJA0 VQLxKLymI1V+L619sAol+LlU5fULl0AvcyYaNkP78m6WIhNLKqPTLIT9S VS88eUrBVUi54tCjgtPE6N6NxNj+Ze7FRZKZoCPP4Y3zK5AYCRnZDNDu1 w==; X-CSE-ConnectionGUID: hdQB8xN8RGmlmfMTbdsXyA== X-CSE-MsgGUID: 54zkYjCZSw6BLItfxSYTEw== X-IronPort-AV: E=McAfee;i="6600,9927,11039"; a="8454002" X-IronPort-AV: E=Sophos;i="6.07,193,1708416000"; d="scan'208";a="8454002" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2024 03:38:54 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,11039"; a="915459875" X-IronPort-AV: E=Sophos;i="6.07,193,1708416000"; d="scan'208";a="915459875" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.54]) by fmsmga002.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2024 03:38:50 -0700 Received: from andy by smile with local (Exim 4.97) (envelope-from ) id 1rurpP-00000003K7E-0KHQ; Thu, 11 Apr 2024 13:38:47 +0300 Date: Thu, 11 Apr 2024 13:38:46 +0300 From: Andy Shevchenko To: Kyle Meyer Cc: linux-kernel@vger.kernel.org, yury.norov@gmail.com, linux@rasmusvillemoes.dk, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, russ.anderson@hpe.com, dimitri.sivanich@hpe.com, steve.wahl@hpe.com Subject: Re: [PATCH v2 2/2] sched/topology: Optimize topology_span_sane() Message-ID: References: <20240410213311.511470-1-kyle.meyer@hpe.com> <20240410213311.511470-3-kyle.meyer@hpe.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240410213311.511470-3-kyle.meyer@hpe.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Wed, Apr 10, 2024 at 04:33:11PM -0500, Kyle Meyer wrote: > Optimize topology_span_sane() by removing duplicate comparisons. > > Since topology_span_sane() is called inside of for_each_cpu(), each > pervious CPU has already been compared against every other CPU. The previous > current CPU only needs to be compared against higher-numbered CPUs. > > The total number of comparisons is reduced from N * (N - 1) to > N * (N - 1) / 2 on each non-NUMA scheduling domain level. Thank you, now it makes sense. -- With Best Regards, Andy Shevchenko