From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FF7FC43334 for ; Wed, 13 Jul 2022 03:47:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230280AbiGMDrS (ORCPT ); Tue, 12 Jul 2022 23:47:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229732AbiGMDrQ (ORCPT ); Tue, 12 Jul 2022 23:47:16 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F083D860C for ; Tue, 12 Jul 2022 20:47:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657684035; x=1689220035; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=GQ/WFbp6QqzRmi3ia7CHLxlH1IRb5fnmp9vJsSIn6JE=; b=nanpZtl+2wivTdsoOoI4Zdv6AzWHsST03GS6ElbpStHLtXr7lEP1J8Lo NkyVJOwArid/LT6L9t9q6bOiRQOJNZi6CnAEZBGlHfc0qtiodBDb4/r/h lkdSxW+udrS80hIke4kRX5/z/2xgxoyvisWZnKvXwSzuTba8Z3jvi/8R4 JTO7EHd7EnzmUxJ5pI+qpJYe098hKeEUm3TMtoqnKndLOGKZ5fpcDQe// mbLcLmDQ4xuuprwsOt+MgR6oLyd7T+rX7AzB25CCZzshrNlKSDuKf572O EENiLTVQt31NkC3Vlv6oVJgcLDmJGUJSEODlTCB8lgyMhLbVXyl7+sSlV A==; X-IronPort-AV: E=McAfee;i="6400,9594,10406"; a="371414512" X-IronPort-AV: E=Sophos;i="5.92,266,1650956400"; d="scan'208";a="371414512" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2022 20:47:15 -0700 X-IronPort-AV: E=Sophos;i="5.92,266,1650956400"; d="scan'208";a="653188428" Received: from yunliu1-mobl.ccr.corp.intel.com (HELO chenyu5-mobl1) ([10.249.171.118]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2022 20:47:13 -0700 Date: Wed, 13 Jul 2022 11:47:08 +0800 From: Chen Yu To: Abel Wu Cc: Peter Zijlstra , Mel Gorman , Vincent Guittot , Josh Don , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/5] sched/fair: ignore SIS_UTIL when has idle core Message-ID: <20220713034708.GA23431@chenyu5-mobl1> References: <20220712082036.5130-1-wuyun.abel@bytedance.com> <20220712082036.5130-2-wuyun.abel@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220712082036.5130-2-wuyun.abel@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2022 at 04:20:32PM +0800, Abel Wu wrote: > When SIS_UTIL is enabled, SIS domain scan will be skipped if > the LLC is overloaded. Since the overloaded status is checked > in the load balancing at LLC level, the interval is llc_size > miliseconds. The duration might be long enough to affect the > overall system throughput if idle cores are out of reach in > SIS domain scan. The idle core scan was skipped in SIS_UTIL because we saw better improvement in some benchmarks. But yes, we could make has_idle_core to scan anyway no matter what the system load is, if we have some data to support it. I'll test this patch on top of latest sched/core branch to see if this makes a difference. thanks, Chenyu > > Signed-off-by: Abel Wu > --- > kernel/sched/fair.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index a78d2e3b9d49..cd758b3616bd 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6392,16 +6392,19 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > struct sched_domain *this_sd; > u64 time = 0; > > - this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); > - if (!this_sd) > - return -1; > - > cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); > > - if (sched_feat(SIS_PROP) && !has_idle_core) { > + if (has_idle_core) > + goto scan; > + > + if (sched_feat(SIS_PROP)) { > u64 avg_cost, avg_idle, span_avg; > unsigned long now = jiffies; > > + this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); > + if (!this_sd) > + return -1; > + > /* > * If we're busy, the assumption that the last idle period > * predicts the future is flawed; age away the remaining > @@ -6436,7 +6439,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > return -1; > } > } > - > +scan: > for_each_cpu_wrap(cpu, cpus, target + 1) { > if (has_idle_core) { > i = select_idle_core(p, cpu, cpus, &idle_cpu); > -- > 2.31.1 >