From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 10EC9288C3D for ; Tue, 28 Oct 2025 17:06:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761671197; cv=none; b=e6VFaDosQhIKih912qSE5MPYm7+tiKECAkXsroalUF8WY7ZhWL4vl+l1ZOHKv6xfkn23CgN/3K84EhutfSwgqq2hO/n6QzGW4GiCk911b+/7ApFjjcVEf4oKNVmavAOcIIORXslMEduvIfQpY0gqgHaQGudaTJ/AD8WVRhRf2I0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761671197; c=relaxed/simple; bh=1fRCFqCI/ZAvNd/ktogPG/ORwomJRauu8jGRPo54Svw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=rGET9xmFJ7csX6wR192XHwa3R5ZT4EdQbdru9v1tMfiVvvFv+OcbZBXt59i+aay5W0V/DqeeF0ud1MGOZ4mS41SlFocIvisQTUfoi8HTJHU0dtlak0+KMYbV1RWUs+3cWv6qQJ1cs/ffmSe+8VFwtdpAvLVJ0+9sHUsknQjy6ow= 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=lDVuiocb; arc=none smtp.client-ip=192.198.163.8 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="lDVuiocb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1761671191; x=1793207191; h=message-id:subject:from:to:cc:date:in-reply-to: references:content-transfer-encoding:mime-version; bh=1fRCFqCI/ZAvNd/ktogPG/ORwomJRauu8jGRPo54Svw=; b=lDVuiocbbnUi+FPTXzKMFzSBn5zPWTTX7N08AGSUq4BHiOTvjtM6AGDG 2g8Q+00yy5ZMlVwlfMbknlekQk6wA5BemXZsabb8rgYhfsUSKw2/VHal6 jXkCGifGkRlnjF8hEEwtFy+CGfEbBir2FT09RnR6vnthm+O6cpduROL8i qXfGitNZrNkRQWmi88u67yFdF8e6NptshGfkrIWoisItpMrh4pM7bZkwn dgTQPzR9AX2wTFsV4/kS1O3QuvcnF2Vi7sr5Q+Ho7u3kBYLCpFREw4t+L OKaYjrTp+reGr32L9MzYo7qc5vciHGmycB6L2rFtekJ1b4zxjQrZ7fN4B Q==; X-CSE-ConnectionGUID: BjQ8PKQFQWCb67+AWMFaFQ== X-CSE-MsgGUID: iVIK6X2fRLKWJrbNmihyHA== X-IronPort-AV: E=McAfee;i="6800,10657,11586"; a="81409946" X-IronPort-AV: E=Sophos;i="6.19,261,1754982000"; d="scan'208";a="81409946" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2025 10:06:30 -0700 X-CSE-ConnectionGUID: pEKwIVaQTFiG5cn3iDp5wQ== X-CSE-MsgGUID: vm7DQprKSLK1QmkPZeb+zg== X-ExtLoop1: 1 Received: from unknown (HELO [10.241.243.18]) ([10.241.243.18]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2025 10:06:29 -0700 Message-ID: <23a9460132e9221bdfe91c334d4850e15ac6178c.camel@linux.intel.com> Subject: Re: [PATCH 07/19] sched/fair: Track LLC-preferred tasks per runqueue From: Tim Chen To: K Prateek Nayak , Peter Zijlstra , Ingo Molnar , "Gautham R . Shenoy" Cc: Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Madadi Vineeth Reddy , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Chen Yu , Libo Chen , Adam Li , Tim Chen , linux-kernel@vger.kernel.org Date: Tue, 28 Oct 2025 10:06:28 -0700 In-Reply-To: References: Autocrypt: addr=tim.c.chen@linux.intel.com; prefer-encrypt=mutual; keydata=mQENBE6N6zwBCADFoM9QBP6fLqfYine5oPRtaUK2xQavcYT34CBnjTlhbvEVMTPlNNzE5 v04Kagcvg5wYcGwr3gO8PcEKieftO+XrzAmR1t3PKxlMT1bsQdTOhKeziZxh23N+kmA7sO/jnu/X2 AnfSBBw89VGLN5fw9DpjvU4681lTCjcMgY9KuqaC/6sMbAp8uzdlue7KEl3/D3mzsSl85S9Mk8KTL MLb01ILVisM6z4Ns/X0BajqdD0IEQ8vLdHODHuDMwV3veAfnK5G7zPYbQUsK4+te32ruooQFWd/iq Rf815j6/sFXNVP/GY4EWT08UB129Kzcxgj2TEixe675Nr/hKTUVKM/NrABEBAAGJAS4EIAECABgFA k6ONYoRHQFLZXkgaXMgcmVwbGFjZWQACgkQHH3vaoxLv2UmbAgAsqa+EKk2yrDc1dEXbZBBGeCiVP XkP7iajI/FiMVZHFQpme4vpntWhg0BIKnF0OSyv0wgn3wzBWx0Zh3cve/PICIj268QvXkb0ykVcIo RnWwBeavO4dd304Mzhz5fBzJwjYx06oabgUmeGawVCEq7UfXy+PsdQdoTabsuD1jq0MbOL/4sB6CZ c4V2mQbW4+Js670/sAZSMj0SQzK9CQyQdg6Wivz8GgTBjWwWsfMt4g2u0s6rtBo8NUZG/yw6fNdao DaT/OCHuBopGmsmFXInigwOXsjyp15Yqs/de3S2Nu5NdjJUwmN1Qd1bXEc/ItvnrFB0RgoNt2gzf2 5aPifLabQlVGltIENoZW4gPHRpbS5jLmNoZW5AbGludXguaW50ZWwuY29tPokBOAQTAQIAIgUCTo3 rPAIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQHH3vaoxLv2XYdAf8DgRO4eIAtWZy4zLv 0EZHWiJ35GYAQ5fPFWBoNURE0+vICrvLyfCKTlUTFxFxTiAWHUO7JM+uBHQSJVsE+ERmTPsiUO1m7 SxZakGy9U2WOEiWMZMRp7HZE8vPUY5AM1OD0b38WBeUD3FPx5WRlQ0z6izF9aIHxoQhci0/WtmGLO Pw3HUlCy1c4DDl6cInpy/JqUPcYlvsp+bWbdm7R5b33WW2CNVVr1eLj+1UP0Iow4jlLzNLW+jOpiv LDs3G/bNC1Uu/SAzTvbaDBRRO9ToX5rlg3Zi8PmOUXWzEfO6N+L1gFCAdYEB4oSOghSbk2xCC4DRl UTlYoTJCRsjusXEy4ZkCDQROjjboARAAtXPJWkNkK3s22BXrcK8w9L/Kzqmp4+V9Y5MkkK94Zv66l XAybnXH3UjL9ATQgo7dnaHxcVX0S9BvHkEeKqEoMwxg86Bb2tzY0yf9+E5SvTDKLi2O1+cd7F3Wba 1eM4Shr90bdqLHwEXR90A6E1B7o4UMZXD5O3MI013uKN2hyBW3CAVJsYaj2s9wDH3Qqm4Xe7lnvTA GV+zPb5Oj26MjuD4GUQLOZVkaA+GX0TrUlYl+PShJDuwQwpWnFbDgyE6YmlrWVQ8ZGFF/w/TsRgJM ZqqwsWccWRw0KLNUp0tPGig9ECE5vy1kLcMdctD+BhjF0ZSAEBOKyuvQQ780miweOaaTsADu5MPGk d3rv7FvKdNencd+G1BRU8GyCyRb2s6b0SJnY5mRnE3L0XfEIJoTVeSDchsLXwPLJy+Fdd2mTWQPXl nforgfKmX6BYsgHhzVsy1/zKIvIQey8RbhBp728WAckUvN47MYx9gXePW04lzrAGP2Mho+oJfCpI0 myjpI9CEctvJy4rBXRgb4HkK72i2gNOlXsabZqy46dULcnrMOsyCXj6B1CJiZbYz4xb8n5LiD31SA fO5LpKQe/G4UkQOZgt+uS7C0Zfp61+0mrhKPG+zF9Km1vaYNH8LIsggitIqE05uCFi9sIgwez3oiU rFYgTkTSqMQNPdweNgVhSUAEQEAAbQ0VGltIENoZW4gKHdvcmsgcmVsYXRlZCkgPHRpbS5jLmNoZW 5AbGludXguaW50ZWwuY29tPokCVQQTAQgAPwIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AWIQT RofI2lb24ozcpAhyiZ7WKota4SQUCYjOVvwUJF2fF1wAKCRCiZ7WKota4SeetD/4hztE+L/Z6oqIY lJJGgS9gjV7c08YH/jOsiX99yEmZC/BApyEpqCIs+RUYl12hwVUJc++sOm/p3d31iXvgddXGYxim0 0+DIhIu6sJaDzohXRm8vuB/+M/Hulv+hTjSTLreAZ9w9eYyqffre5AlEk/hczLIsAsYRsqyYZgjfX Lk5JN0L7ixsoDRQ5syZaY11zvo3LZJX9lTw0VPWlGeCxbjpoQK91CRXe9dx/xH/F/9F203ww3Ggt4 VlV6ZNdl14YWGfhsiJU2rbeJ930sUDbMPJqV60aitI93LickNG8TOLG5QbN9FzrOkMyWcWW7FoXwT zxRYNcMqNVQbWjRMqUnN6PXCIvutFLjLF6FBe1jpk7ITlkS1FvA2rcDroRTU/FZRnM1k0K4GYYYPj 11Zt3ZBcPoI0J3Jz6P5h6fJioqlhvZiaNhYneMmfvZAWJ0yv+2c5tp2aBmKsjmnWecqvHL5r/bXez iKRdcWyXqrEEj6OaJr3S4C0MIgGLteARvbMH+3tNTDIqFuyqdzHLKwEHuvKxHzYFyV7I5ZEQ2HGH5 ZRZ2lRpVjSIlnD4L1PS6Bes+ALDrWqksbEuuk+ixFKKFyIsntIM+qsjkXseuMSIG5ADYfTla9Pc5f VpWBKX/j0MXxdQsxT6tiwE7P+osbOMwQ6Ja5Qi57hj8jBRF1znDjDZkBDQRcCwpgAQgAl12VXmQ1X 9VBCMC+eTaB0EYZlzDFrW0GVmi1ii4UWLzPo0LqIMYksB23v5EHjPvLvW/su4HRqgSXgJmNwJbD4b m1olBeecIxXp6/S6VhD7jOfi4HACih6lnswXXwatzl13OrmK6i82bufaXFFIPmd7x7oz5Fuf9OQlL OnhbKXB/bBSHXRrMCzKUJKRia7XQx4gGe+AT6JxEj6YSvRT6Ik/RHpS/QpuOXcziNHhcRPD/ZfHqJ SEa851yA1J3Qvx1KQK6t5I4hgp7zi3IRE0eiObycHJgT7nf/lrdAEs7wrSOqIx5/mZ5eoKlcaFXiK J3E0Wox6bwiBQXrAQ/2yxBxVwARAQABtCVUaW0gQ2hlbiA8dGltLmMuY2hlbkBsaW51eC5pbnRlbC 5jb20+iQFUBBMBCAA+FiEEEsKdz9s94XWwiuG96lQbuGeTCYsFAlwLCmACGwMFCQHhM4AFCwkIBwI GFQoJCAsCBBYCAwECHgECF4AACgkQ6lQbuGeTCYuQiQf9G2lkrkRdLjXehwCl+k5zBkn8MfUPi2It U2QDcBit/YyaZpNlSuh8h30gihp5Dlb9BnqBVKxooeIVKSKC1HFeG0AE28TvgCgEK8qP/LXaSzGvn udek2zxWtcsomqUftUWKvoDRi1AAWrPQmviNGZ4caMd4itKWf1sxzuH1qF5+me6eFaqhbIg4k+6C5 fk3oDBhg0zr0gLm5GRxK/lJtTNGpwsSwIJLtTI3zEdmNjW8bb/XKszf1ufy19maGXB3h6tA9TTHOF nktmDoWJCq9/OgQS0s2D7W7f/Pw3sKQghazRy9NqeMbRfHrLq27+Eb3Nt5PyiQuTE8JeAima7w98q uQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-10-27 at 11:34 +0530, K Prateek Nayak wrote: > Hello Tim, >=20 > On 10/11/2025 11:54 PM, Tim Chen wrote: > > @@ -3999,6 +4038,7 @@ account_entity_enqueue(struct cfs_rq *cfs_rq, str= uct sched_entity *se) > > struct rq *rq =3D rq_of(cfs_rq); > > =20 > > account_numa_enqueue(rq, task_of(se)); > > + account_llc_enqueue(rq, task_of(se)); > > list_add(&se->group_node, &rq->cfs_tasks); > > } > > cfs_rq->nr_queued++; > > @@ -4010,9 +4050,14 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, st= ruct sched_entity *se) > > update_load_sub(&cfs_rq->load, se->load.weight); > > if (entity_is_task(se)) { > > account_numa_dequeue(rq_of(cfs_rq), task_of(se)); > > + account_llc_dequeue(rq_of(cfs_rq), task_of(se)); > > list_del_init(&se->group_node); > > } > > cfs_rq->nr_queued--; > > + > > + /* safeguard to clear the cache aware data */ > > + if (!parent_entity(se) && !cfs_rq->nr_queued) > > + reset_llc_stats(rq_of(cfs_rq)); >=20 > Instead of relying on reset_llc_stats() hack, I think a better approach > would be to have a "p->se.llc_sched_active" flag similar to how uclamp > has "uc_se->active" and we set this in account_llc_enqueue() which will > still check for sched_cache_enabled() but account_llc_dequeue() would > only check for "p->se.llc_sched_active" to decrement the stats and then > unset the flag. >=20 > That way, we cannot have an imbalanced accounting. Thoughts? With our current accounting method, we should not have imbalanced accounting even if you turn on sched_cache after the scheduler has started running (see my reply to Chen Yu's follow up). That reset_llc_stats() hack should not be needed as Peter pointed out. We will change that check to warning under debug option. Tim >=20 > > } > > =20