From patchwork Thu Dec 3 14:11:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mel Gorman X-Patchwork-Id: 11948947 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7639FC00130 for ; Thu, 3 Dec 2020 14:13:20 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0E28420757 for ; Thu, 3 Dec 2020 14:13:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E28420757 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=bmumf/KAe/x8Od8ggOL6s8VCcCxRUiwN96dD8HTKD80=; b=IJuktPDarP2F7ykUVvyQW4+wf MMfCo7woHu07rz2kYUGM5lmS8buC/AGa7Mti9rTMlQhNT8x4GywE41JoEAFGXvFvo7FnjlwK9/EyX rXzPmYTq0y+xtTDcZruWsQeZDMelhPNnZQG8tiEIxZcH5VJE5bs8y/Se3zDqmkh2kC1SeSV4RteYA cY/FKW7r8OaniWDksNvj3J62Oy6CW5qG/6pTplePwkJdx2d0sUV5n+z8iw+HT2p6L1sYjufVkZXgl 7XjnMS11Rf1HlZ6jUAC8WgbcjAvFz9vqKzqeKJOfL/QOR4NG7ofXpPu7W7P6eWe1pFyiNup3Olane c/VsDfH2A==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkpKp-0003pI-Au; Thu, 03 Dec 2020 14:11:51 +0000 Received: from outbound-smtp45.blacknight.com ([46.22.136.57]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkpKS-0003gd-KL for linux-arm-kernel@lists.infradead.org; Thu, 03 Dec 2020 14:11:32 +0000 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp45.blacknight.com (Postfix) with ESMTPS id 39555FA8FC for ; Thu, 3 Dec 2020 14:11:25 +0000 (GMT) Received: (qmail 22688 invoked from network); 3 Dec 2020 14:11:25 -0000 Received: from unknown (HELO stampy.112glenside.lan) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPA; 3 Dec 2020 14:11:24 -0000 From: Mel Gorman To: LKML Subject: [PATCH 02/10] sched/fair: Track efficiency of task recent_used_cpu Date: Thu, 3 Dec 2020 14:11:16 +0000 Message-Id: <20201203141124.7391-3-mgorman@techsingularity.net> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201203141124.7391-1-mgorman@techsingularity.net> References: <20201203141124.7391-1-mgorman@techsingularity.net> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201203_091128_938031_1D7643F8 X-CRM114-Status: GOOD ( 16.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Barry Song , Juri Lelli , Vincent Guittot , Peter Ziljstra , Aubrey Li , Ingo Molnar , Mel Gorman , Valentin Schneider , Linux-ARM Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This simply tracks the efficiency of the recent_used_cpu. The hit rate of this matters as it can avoid a domain search. Similarly, the miss rate matters because each miss is a penalty to the fast path. It is not required that this patch be merged with the series but if we are looking at the usefulness of p->recent_used_cpu, the stats generate hard data on what the hit rate is. MMTests uses this to generate additional metrics. SIS Recent Used Hit: A recent CPU was eligible and used. Each hit is a domain search avoided. SIS Recent Used Miss: A recent CPU was eligible but unavailable. Each time this is miss, there was a small penalty to the fast path before a domain search happened. SIS Recent Success Rate: A percentage of the number of hits versus the total attempts to use the recent CPU. SIS Recent Attempts: The total number of times the recent CPU was examined. A high number of Recent Attempts with a low Success Rate implies the fast path is being punished severely. This could have been presented as a weighting of hits and misses but calculating an appropriate weight for misses is problematic. Signed-off-by: Mel Gorman --- kernel/sched/debug.c | 2 ++ kernel/sched/fair.c | 23 +++++++++++++---------- kernel/sched/sched.h | 2 ++ kernel/sched/stats.c | 7 ++++--- 4 files changed, 21 insertions(+), 13 deletions(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 2386cc5e79e5..8f933a9e8c25 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -718,6 +718,8 @@ do { \ P(sis_domain_search); P(sis_scanned); P(sis_failed); + P(sis_recent_hit); + P(sis_recent_miss); } #undef P diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 494ba01f3414..d9acd55d309b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6291,16 +6291,19 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) recent_used_cpu = p->recent_used_cpu; if (recent_used_cpu != prev && recent_used_cpu != target && - cpus_share_cache(recent_used_cpu, target) && - (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) && - cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && - asym_fits_capacity(task_util, recent_used_cpu)) { - /* - * Replace recent_used_cpu with prev as it is a potential - * candidate for the next wake: - */ - p->recent_used_cpu = prev; - return recent_used_cpu; + cpus_share_cache(recent_used_cpu, target)) { + if ((available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) && + cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && + asym_fits_capacity(task_util, recent_used_cpu)) { + /* + * Replace recent_used_cpu with prev as it is a potential + * candidate for the next wake: + */ + p->recent_used_cpu = prev; + schedstat_inc(this_rq()->sis_recent_hit); + return recent_used_cpu; + } + schedstat_inc(this_rq()->sis_recent_miss); } /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 90a62dd9293d..6a6578c4c24b 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1055,6 +1055,8 @@ struct rq { unsigned int sis_domain_search; unsigned int sis_scanned; unsigned int sis_failed; + unsigned int sis_recent_hit; + unsigned int sis_recent_miss; #endif #ifdef CONFIG_CPU_IDLE diff --git a/kernel/sched/stats.c b/kernel/sched/stats.c index 390bfcc3842c..402fab75aa14 100644 --- a/kernel/sched/stats.c +++ b/kernel/sched/stats.c @@ -10,7 +10,7 @@ * Bump this up when changing the output format or the meaning of an existing * format, so that tools can adapt (or abort) */ -#define SCHEDSTAT_VERSION 16 +#define SCHEDSTAT_VERSION 17 static int show_schedstat(struct seq_file *seq, void *v) { @@ -30,14 +30,15 @@ static int show_schedstat(struct seq_file *seq, void *v) /* runqueue-specific stats */ seq_printf(seq, - "cpu%d %u 0 %u %u %u %u %llu %llu %lu %u %u %u %u", + "cpu%d %u 0 %u %u %u %u %llu %llu %lu %u %u %u %u %u %u", cpu, rq->yld_count, rq->sched_count, rq->sched_goidle, rq->ttwu_count, rq->ttwu_local, rq->rq_cpu_time, rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount, rq->sis_search, rq->sis_domain_search, - rq->sis_scanned, rq->sis_failed); + rq->sis_scanned, rq->sis_failed, + rq->sis_recent_hit, rq->sis_recent_miss); seq_printf(seq, "\n");