From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 2782F23D7FD for ; Wed, 15 Oct 2025 15:10:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760541034; cv=none; b=U/bNkwSO7r+wKqy7CDv24qMtmZ9SXdP5NTePez0sAgfznOnthJQRWkzGtt9LqM9OT8GBFXUgHfWwECN386SaDHByEn/ApZM1nTZ0B4hypZfS1Tyt7MltI0kuDUx6mD2RMYcjhCc3Ge4be/eR3U4Sbx048cnPlFtpM8XbPOZelGs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760541034; c=relaxed/simple; bh=f14PWbULMh4v8PUO7qDTRoj0XcDJtts3b8JSLTkxNg0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FxTw3y6xhYjO8UgmwevJ/tqMeOW+UjZc0tSe30TMDzI8DTk9w2zzaM5E/gRgeCIa2ryNMQw9r5yJsTyCwyrH6WrLTOJjQfeXkUwY94PVNdjAMh2jT76mwoHkPeWd7pLuTfpEbm1bTIXesJA2COzyMYd4QyXaMewEcPg+0wVsdAE= 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=DRWvjIFv; arc=none smtp.client-ip=90.155.50.34 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="DRWvjIFv" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=4wgEq49IB0uLqTXuKXqfa6en+AWfDLw0/Bbku+CO7No=; b=DRWvjIFvOw33hFMjIZ8ue3UWJB y3SMtHZmVBT3TfYfuPh0yAvX5mkvYFkV8w1hpa2d45NXyQJE639C6EBuJBCjJta0ACnLLRSRnQmoR 4izR3OMsXd5Slr3GXrWjki2yUiw3yq0orD3WXBnGBq11ZFDJNoMNiqwIe1/xQJ3F4xtT7ZBtfSFaS M6Mx4ThybAPzmTtonLcirCKQR6cXBSvlCFHqFEcxV3oZUL30TrV6+ifALukRETGSyyUWrx2TzAZ3V JrM9UNWw+pj4/R6ijZdttMrjnd0v1esEhE9OgjX3NzSFkBt0bde4Mqv1wJRtqgPZxGwFROg3b/p6v TZzpXtKA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v938e-00000000cPL-3SrN; Wed, 15 Oct 2025 15:10:06 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 9CEE5300325; Wed, 15 Oct 2025 17:10:05 +0200 (CEST) Date: Wed, 15 Oct 2025 17:10:05 +0200 From: Peter Zijlstra To: Tim Chen Cc: Ingo Molnar , K Prateek Nayak , "Gautham R . Shenoy" , 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 Subject: Re: [PATCH 10/19] sched/fair: Prioritize tasks preferring destination LLC during balancing Message-ID: <20251015151005.GC3168635@noisy.programming.kicks-ass.net> References: 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: On Sat, Oct 11, 2025 at 11:24:47AM -0700, Tim Chen wrote: > +static inline bool llc_balance(struct lb_env *env, struct sg_lb_stats *sgs, > + struct sched_group *group) > +{ > + struct sched_domain *child = env->sd->child; > + int llc; > + > + if (!sched_cache_enabled()) > + return false; > + > + if (env->sd->flags & SD_SHARE_LLC) > + return false; > + > + /* only care about task migration among LLCs */ > + if (child && !(child->flags & SD_SHARE_LLC)) > + return false; > + > + llc = llc_idx(env->dst_cpu); > + if (sgs->nr_pref_llc[llc] > 0 && Robot says llc can be -1 here, and it don't like doing out of bound array access. > + can_migrate_llc(env->src_cpu, env->dst_cpu, 0, true) == mig_llc) > + return true; > + > + return false; > +}