From patchwork Mon May 10 12:05:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 12247969 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE 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 EE23FC433ED for ; Mon, 10 May 2021 13:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C72CC6157E for ; Mon, 10 May 2021 13:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344849AbhEJMx7 (ORCPT ); Mon, 10 May 2021 08:53:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245646AbhEJMNe (ORCPT ); Mon, 10 May 2021 08:13:34 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7788DC0611CC; Mon, 10 May 2021 05:05:41 -0700 (PDT) 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=hgWKawcsmXyf/l2+3vEwOhYJ9xgud2VHY8Z8IPJF1w8=; b=k42pJsX2WLlKvruyN8PNJivDyZ ffOn188g03X9FmI6TkpJONi0Qz2pdy2kB9vYEHDDxtQlChs7w92Pfb+Uz8BonqjueTs1HqWZeErpj pOBBZ20ra5bGCrmwqIh930icE2Ri940t6qJfHWg26uauAi2UOREq+fJhILXRNRjPMGf12iWaJ1lJC Hh4R/UOxTDRblhm89WOSYb6K3cEZUi1WID/rUepmD6pbzAd5FH1R0+iMqeEEp8A4X3sw6XxuhPIJk J4mnk9jkHDWOBZ4YTPN7zcl1IIkSqdBwuefml5auPMtlR0ULkuKyy4Q1q88WTvmba+shetUGvHvIe l3qCOUbA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lg4ez-00EBfk-H3; Mon, 10 May 2021 12:05:18 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9B9A63002C4; Mon, 10 May 2021 14:05:13 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8077C20275859; Mon, 10 May 2021 14:05:13 +0200 (CEST) Date: Mon, 10 May 2021 14:05:13 +0200 From: Peter Zijlstra To: tglx@linutronix.de, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, bsingharora@gmail.com, pbonzini@redhat.com, maz@kernel.org Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, riel@surriel.com, hannes@cmpxchg.org Subject: [PATCH 7/6] delayacct: Add sysctl to enable at runtime Message-ID: References: <20210505105940.190490250@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210505105940.190490250@infradead.org> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Just like sched_schedstats, allow runtime enabling (and disabling) of delayacct. This is useful if one forgot to add the delayacct boot time option. Signed-off-by: Peter Zijlstra (Intel) --- Documentation/accounting/delay-accounting.rst | 6 ++-- kernel/delayacct.c | 36 ++++++++++++++++++++++++-- kernel/sysctl.c | 12 ++++++++ 3 files changed, 50 insertions(+), 4 deletions(-) --- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -74,8 +74,10 @@ Delay accounting is disabled by default delayacct -to the kernel boot options. The rest of the instructions -below assume this has been done. +to the kernel boot options. The rest of the instructions below assume this has +been done. Alternatively, use sysctl kernel.sched_delayacct to switch the state +at runtime. Note however that only tasks started after enabling it will have +delayacct information. After the system has booted up, use a utility similar to getdelays.c to access the delays --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -18,6 +18,17 @@ DEFINE_STATIC_KEY_FALSE(delayacct_key); int delayacct_on __read_mostly; /* Delay accounting turned on/off */ struct kmem_cache *delayacct_cache; +static void set_delayacct(bool enabled) +{ + if (enabled) { + static_branch_enable(&delayacct_key); + delayacct_on = 1; + } else { + delayacct_on = 0; + static_branch_disable(&delayacct_key); + } +} + static int __init delayacct_setup_enable(char *str) { delayacct_on = 1; @@ -29,9 +40,30 @@ void delayacct_init(void) { delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); delayacct_tsk_init(&init_task); - if (delayacct_on) - static_branch_enable(&delayacct_key); + set_delayacct(delayacct_on); +} + +#ifdef CONFIG_PROC_SYSCTL +int sysctl_delayacct(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + int state = delayacct_on; + struct ctl_table t; + int err; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + t = *table; + t.data = &state; + err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); + if (err < 0) + return err; + if (write) + set_delayacct(state); + return err; } +#endif void __delayacct_tsk_init(struct task_struct *tsk) { --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -71,6 +71,7 @@ #include #include #include +#include #include "../lib/kstrtox.h" @@ -1727,6 +1728,17 @@ static struct ctl_table kern_table[] = { .extra2 = SYSCTL_ONE, }, #endif /* CONFIG_SCHEDSTATS */ +#ifdef CONFIG_TASK_DELAY_ACCT + { + .procname = "sched_delayacct", + .data = NULL, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sysctl_delayacct, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +#endif /* CONFIG_TASK_DELAY_ACCT */ #ifdef CONFIG_NUMA_BALANCING { .procname = "numa_balancing",