From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.21]) (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 1CE1D364952 for ; Thu, 26 Feb 2026 18:14:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772129664; cv=none; b=e6T6r1XYSIBTvBO2PB683yxxiXIj+8awmp7qtGWQ9o4nGvMrI2xsmLOnwuVfoDP2fif8exjF7KKS9kPB1Hd9nvlSx+5WIybea2Kq/7QFxOmTdZTxVC4iItxD7x4Ciu4gLr7yvJ1MGWr8RfCSkLt5vnlD8RGee0VZ9rl6sFzhaKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772129664; c=relaxed/simple; bh=mvnFeWfI/vsnjVZ3mEFThFXmrCs4izlRrsHXByBNpPQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=snlwdihZ1M+w4arEipkMhIOSDiWeRCcCEzcvjTAcpWFU19Bd6SR8z72OBDqL/vRnNoBeMyE5C53GPHTPOklfvNV5mfLcH7yknp+boMGgNuh6Yo5ds4PDxjBPEQYwAa1VaczV6W2qWeK43nBpQucsVa8Nc/Wran6ZQEnJIa5gjsk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=RQwL7/o7; arc=none smtp.client-ip=198.175.65.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass 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="RQwL7/o7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1772129663; x=1803665663; h=message-id:subject:from:to:cc:date:in-reply-to: references:content-transfer-encoding:mime-version; bh=mvnFeWfI/vsnjVZ3mEFThFXmrCs4izlRrsHXByBNpPQ=; b=RQwL7/o7/z77Ip11ugiTzXnCWPEoA107iVeUZRE8wsiJstQ6GY2rRU9T cjbPqiS/gCeiy9IIzqeysEJK1fwaZfvez/tOnascBq7smyW12hnAQ3tUC nJg48+Znm+1Y97yVNYXMdAbkNdyB3byBu/eNmtwtsiXp1vEm7IcXE46AL u7NJGb5tb0D7nJHqc0QSRlHTniuAxbO/nJq40SowwJsTegFVS24AU+9QH EK0Oex7GtNU1D2UHxRjvjm5D49UoU0V0MdTOyaMdJUdXSk23wsWDFM1uE Ywx51BsWYnu0xtHoel1aKpb30cFOoPJJPM6qknmHjzw2LY1tque0neTSP g==; X-CSE-ConnectionGUID: VdEGVWaRRk2SaY/80OYQUQ== X-CSE-MsgGUID: j8T/zGePSVKuZjs594PPqg== X-IronPort-AV: E=McAfee;i="6800,10657,11713"; a="73072246" X-IronPort-AV: E=Sophos;i="6.21,312,1763452800"; d="scan'208";a="73072246" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Feb 2026 10:14:22 -0800 X-CSE-ConnectionGUID: 6SPGXhlWRIa1bhPyBUKmUw== X-CSE-MsgGUID: GUSMn8dtT4+ygvjOUsrwKA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,312,1763452800"; d="scan'208";a="239635827" Received: from schen9-mobl4.amr.corp.intel.com (HELO [10.125.111.161]) ([10.125.111.161]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Feb 2026 10:14:22 -0800 Message-ID: <85409d18a54e30a4b936ba18198b8f957767c082.camel@linux.intel.com> Subject: Re: [PATCH v2] sched/topology: Check average distances to remote packages From: Tim Chen To: Kyle Meyer Cc: Peter Zijlstra , "Chen, Yu C" , bp@alien8.de, dave.hansen@linux.intel.com, mingo@redhat.com, tglx@kernel.org, vinicius.gomes@intel.com, brgerst@gmail.com, hpa@zytor.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, patryk.wlazlyn@linux.intel.com, rafael.j.wysocki@intel.com, russ.anderson@hpe.com, x86@kernel.org, zhao1.liu@intel.com Date: Thu, 26 Feb 2026 10:14:21 -0800 In-Reply-To: References: <20260223170314.GU1395266@noisy.programming.kicks-ass.net> <20260225123052.GN3016024@noisy.programming.kicks-ass.net> <20260225154409.GD1282955@noisy.programming.kicks-ass.net> <20260225163246.GX1395416@noisy.programming.kicks-ass.net> <62f610811c1b1cba7e282b6e855baba11f7f49a6.camel@linux.intel.com> <20260225223024.GA606826@noisy.programming.kicks-ass.net> 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 Wed, 2026-02-25 at 17:29 -0600, Kyle Meyer wrote: > On Wed, Feb 25, 2026 at 02:55:58PM -0800, Tim Chen wrote: > > On Wed, 2026-02-25 at 23:30 +0100, Peter Zijlstra wrote: > > > On Wed, Feb 25, 2026 at 01:37:11PM -0800, Tim Chen wrote: > > > > On Wed, 2026-02-25 at 17:32 +0100, Peter Zijlstra wrote: > > > > > On Wed, Feb 25, 2026 at 04:44:09PM +0100, Peter Zijlstra wrote: > > > > >=20 > > > > > > Yes, so this assumes that all u sized clusters on the trace are= similar > > > > > > and 'sane' without verification. > > > > >=20 > > > > > That gave me an idea; how's this then? > > > >=20 > > > > Sorry I was sick for a few days. Just catching up on this > > > > thread here. I think your patch takes care of both GNR SNC-3=C2=A0 > > > > with 3 compute dies (with non-symmetric remote > > > > distances) and generic SNC-2 with 2 dies (symmetric > > > > distances) very well. > > > >=20 > > > > Minor suggestion below for the patch. > > > >=20 > > > > Will ask the original GNR teams with the problem to try > > > > it out. > > >=20 > > > Since HPE can obviously have a sane SLIT table; why can't we simply > > > claim the SLIT table they had is broken and needs fixing? > >=20 > > From what I can see HPE seems to use SNC-2 variant of GNR so the SLIT > > is symmetric. >=20 > Yes, and the SKUs that don't support SNC. >=20 > The SKUs that support SNC-3 are limited to 2 packages. Yes, I think there are only 2 packages SNC-3 out there.=20 >=20 > > Unfortunately in the topology for the 2 socket GNR that has 3 dies, the= re > > are truly unsymmetric paths from between die A to die B between remote > > sockets from what I'm told. >=20 > What does MLC look like? I don't have access to one for measurements. Will have to ask colleagues to measure that. >=20 > > > Also, is there really no enumeration of the SNC mode available; must = we > > > really divinate? > >=20 > > Let me dig into that a bit. I was also thinking with that information, > > it will make the code a lot simpler. There's truly no hardware bits to expose the SNC mode. Will have to rely on snc_get_config() and use the ratio of number of CPUs in node vs L3 to get an estimate. Tim