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 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,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 2FAFEC43461 for ; Wed, 5 May 2021 11:21:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E42556121F for ; Wed, 5 May 2021 11:21:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232971AbhEELWS (ORCPT ); Wed, 5 May 2021 07:22:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232965AbhEELV7 (ORCPT ); Wed, 5 May 2021 07:21:59 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADA04C061761; Wed, 5 May 2021 04:21:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=nciwZ+Lsg8fk93SuI4bx84k4rYAnK6nrHeX7lP7LhA8=; b=VuwyUPHSCi4rWDAZAKX+kRkrjD gj8mDz5lZZ/Ki1H2SlM+e3NdiCqVfR9uHSnQcxwfQoL7B8hbx2MgnsTj3SdnWARRwlGo0393j7szp xX2JO3S0PlqL66UNh/UIECnER9mWrh0wZbPHGcbkaXFyzCaEpi4kaL7NAqvlgYd8W3PzdkmAie60B t0QU9JkVBpJIwg6qY1oXXzKqbEiZiukftWqYUJEkepJxdCkOXLwfdybf0tDQi/wbqznZr6G69Y/Op Wep+4hyJxPl34cY8aHqRE9jMOQpFldCA2ukEL5FFoQBgqMilpfSOv2E/Pf9hmZ1eizgu5quUzYdY6 FBK9Ub3w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1leFXn-000FRC-EJ; Wed, 05 May 2021 11:18:44 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 97B0F30030F; Wed, 5 May 2021 13:18:16 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 010EE299E9869; Wed, 5 May 2021 13:18:14 +0200 (CEST) Message-ID: <20210505111525.308018373@infradead.org> User-Agent: quilt/0.66 Date: Wed, 05 May 2021 12:59:46 +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, peterz@infradead.org, riel@surriel.com, hannes@cmpxchg.org Subject: [PATCH 6/6] [RFC] delayacct: Default disabled References: <20210505105940.190490250@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Assuming this stuff isn't actually used much; disable it by default and avoid allocating and tracking the task_delay_info structure. taskstats is changed to still report the regular sched and sched_info and only skip the missing task_delay_info fields instead of not reporting anything. Signed-off-by: Peter Zijlstra (Intel) --- Documentation/accounting/delay-accounting.rst | 8 ++++---- Documentation/admin-guide/kernel-parameters.txt | 2 +- include/linux/delayacct.h | 16 ++++------------ kernel/delayacct.c | 19 +++++++++++-------- 4 files changed, 20 insertions(+), 25 deletions(-) --- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -69,13 +69,13 @@ Usage CONFIG_TASK_DELAY_ACCT=y CONFIG_TASKSTATS=y -Delay accounting is enabled by default at boot up. -To disable, add:: +Delay accounting is disabled by default at boot up. +To enable, add:: - nodelayacct + delayacct to the kernel boot options. The rest of the instructions -below assume this has not been done. +below assume this has been done. After the system has booted up, use a utility similar to getdelays.c to access the delays --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3213,7 +3213,7 @@ noclflush [BUGS=X86] Don't use the CLFLUSH instruction - nodelayacct [KNL] Disable per-task delay accounting + delayacct [KNL] Enable per-task delay accounting nodsp [SH] Disable hardware DSP at boot time. --- a/include/linux/delayacct.h +++ b/include/linux/delayacct.h @@ -61,7 +61,7 @@ struct task_delay_info { #include #ifdef CONFIG_TASK_DELAY_ACCT -DECLARE_STATIC_KEY_TRUE(delayacct_key); +DECLARE_STATIC_KEY_FALSE(delayacct_key); extern int delayacct_on; /* Delay accounting turned on/off */ extern struct kmem_cache *delayacct_cache; extern void delayacct_init(void); @@ -69,7 +69,7 @@ extern void __delayacct_tsk_init(struct extern void __delayacct_tsk_exit(struct task_struct *); extern void __delayacct_blkio_start(void); extern void __delayacct_blkio_end(struct task_struct *); -extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *); +extern int delayacct_add_tsk(struct taskstats *, struct task_struct *); extern __u64 __delayacct_blkio_ticks(struct task_struct *); extern void __delayacct_freepages_start(void); extern void __delayacct_freepages_end(void); @@ -116,7 +116,7 @@ static inline void delayacct_tsk_free(st static inline void delayacct_blkio_start(void) { - if (!static_branch_likely(&delayacct_key)) + if (!static_branch_unlikely(&delayacct_key)) return; delayacct_set_flag(DELAYACCT_PF_BLKIO); @@ -126,7 +126,7 @@ static inline void delayacct_blkio_start static inline void delayacct_blkio_end(struct task_struct *p) { - if (!static_branch_likely(&delayacct_key)) + if (!static_branch_unlikely(&delayacct_key)) return; if (p->delays) @@ -134,14 +134,6 @@ static inline void delayacct_blkio_end(s delayacct_clear_flag(DELAYACCT_PF_BLKIO); } -static inline int delayacct_add_tsk(struct taskstats *d, - struct task_struct *tsk) -{ - if (!delayacct_on || !tsk->delays) - return 0; - return __delayacct_add_tsk(d, tsk); -} - static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk) { if (tsk->delays) --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -14,23 +14,23 @@ #include #include -DEFINE_STATIC_KEY_TRUE(delayacct_key); -int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ +DEFINE_STATIC_KEY_FALSE(delayacct_key); +int delayacct_on __read_mostly; /* Delay accounting turned on/off */ struct kmem_cache *delayacct_cache; -static int __init delayacct_setup_disable(char *str) +static int __init delayacct_setup_enable(char *str) { - delayacct_on = 0; + delayacct_on = 1; return 1; } -__setup("nodelayacct", delayacct_setup_disable); +__setup("delayacct", delayacct_setup_enable); 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_disable(&delayacct_key); + if (delayacct_on) + static_branch_enable(&delayacct_key); } void __delayacct_tsk_init(struct task_struct *tsk) @@ -83,7 +83,7 @@ void __delayacct_blkio_end(struct task_s delayacct_end(&delays->lock, &delays->blkio_start, total, count); } -int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) +int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) { u64 utime, stime, stimescaled, utimescaled; unsigned long long t2, t3; @@ -118,6 +118,9 @@ int __delayacct_add_tsk(struct taskstats d->cpu_run_virtual_total = (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; + if (!tsk->delays) + return 0; + /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ raw_spin_lock_irqsave(&tsk->delays->lock, flags);