From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 A2F5F2ECEAC for ; Wed, 1 Oct 2025 13:17:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759324677; cv=none; b=Lka21z70G8j+rpO9OE8SIoktfPkNcbJuCN0LRGXtPe8yUvEeLb0NhfnLnE53UOT/LbErwLM3uvRWY1nQJlh0tgBt2wxX4DXQosLZFfwfDFEttYNKGVKVPaHUiBp3oxiHafMlPG1lGlBxeGFAQAEhLdc2xFRATzyRIoSrCROMMpg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759324677; c=relaxed/simple; bh=p6Sayqqd2zhgUHb4VCONJK2LH04ksZOZBx9B82RJizQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s/K6h/4AOrplN9sa2wr17HLxNR7L0lUPTe9dFZ3erNK7LR3BjXnzxDtl6KlCpPt3KL1QytAPwF9lu5el/w4ca/2rbzDixGRCHP33Xk1jPR5sPK0zWN8GqtBmSSm//l6OMJRxYwBwf7idX5VWpyAa/N+ITSFDJSq61Hua7OVuDpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=N4FIDRd2; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="N4FIDRd2" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=E8kzoy6QofB6dAgP+yMKbxfNz5D8bf+8F1qEp238yNo=; b=N4FIDRd2oMaNkMPxH81S+p3idM pEsOrEugE0N3i9pecJIM/P8wD0oEpNfT2TyQ2yGTxybfL/LYUfzbfpVmR7qScMLM7fkeXowFE7duJ lnspF5fjPvSRMYMLNS4lcIE1INwAaYdBSN1DUBtKz1miLuTDCH2nxo7ttZo3oTP+T/eI+8/XylIqH ebuj+o7UomPyVL6A6bID8ZXRoeQV9t4mOwILJY8yoGJzEgtuuKDo+uDHIsP31Im26ZHCPNiE+37jY 4uxUSadraEwS/NS8N6dfe09Sz+IRbGi9j3AoXWyaIw6DYxAW6ImYnwuQe8hc8kca8eMLxZ8fkkBmV a8vb1VRg==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v3who-0000000DZQf-4ACq; Wed, 01 Oct 2025 13:17:17 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id B95BB300328; Wed, 01 Oct 2025 15:17:15 +0200 (CEST) Date: Wed, 1 Oct 2025 15:17:15 +0200 From: Peter Zijlstra To: Chen Yu Cc: Ingo Molnar , K Prateek Nayak , "Gautham R . Shenoy" , Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Libo Chen , Madadi Vineeth Reddy , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Len Brown , Tim Chen , Aubrey Li , Zhao Liu , Chen Yu , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v4 07/28] sched: Add helper function to decide whether to allow cache aware scheduling Message-ID: <20251001131715.GO4067720@noisy.programming.kicks-ass.net> References: <701c7be7f0e69582d9ad0c25025ec2e133e73fbb.1754712565.git.tim.c.chen@linux.intel.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: <701c7be7f0e69582d9ad0c25025ec2e133e73fbb.1754712565.git.tim.c.chen@linux.intel.com> On Sat, Aug 09, 2025 at 01:03:10PM +0800, Chen Yu wrote: > From: Tim Chen > > Cache-aware scheduling is designed to aggregate threads into their > preferred LLC, either via the task wake up path or the load balancing > path. One side effect is that when the preferred LLC is saturated, > more threads will continue to be stacked on it, degrading the workload's > latency. A strategy is needed to prevent this aggregation from going too > far such that the preferred LLC is too overloaded. So one of the ideas was to extend the preferred llc number to a mask. Update the preferred mask with (nr_threads / llc_size) bits, indicating the that many top llc as sorted by occupancy.