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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1C7BFC2D0C1 for ; Thu, 19 Dec 2019 14:46:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F14232053B for ; Thu, 19 Dec 2019 14:46:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726847AbfLSOqq (ORCPT ); Thu, 19 Dec 2019 09:46:46 -0500 Received: from relay.sw.ru ([185.231.240.75]:54958 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726767AbfLSOqq (ORCPT ); Thu, 19 Dec 2019 09:46:46 -0500 Received: from dhcp-172-16-24-104.sw.ru ([172.16.24.104]) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1ihx4Y-0006oR-88; Thu, 19 Dec 2019 17:46:38 +0300 Subject: Re: [PATCH RFC] sched: Micro optimization in pick_next_task() and in check_preempt_curr() To: Steven Rostedt Cc: Peter Zijlstra , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org References: <157675913272.349305.8936736338884044103.stgit@localhost.localdomain> <20191219131242.GK2827@hirez.programming.kicks-ass.net> <20191219140252.GS2871@hirez.programming.kicks-ass.net> <20191219094330.0e44c748@gandalf.local.home> From: Kirill Tkhai Message-ID: <11d755e9-e4f8-dd9e-30b0-45aebe260b2f@virtuozzo.com> Date: Thu, 19 Dec 2019 17:46:37 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191219094330.0e44c748@gandalf.local.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19.12.2019 17:43, Steven Rostedt wrote: > On Thu, 19 Dec 2019 17:25:40 +0300 > Kirill Tkhai wrote: > >> (17:19:25) nbjoerg: but it is not guarenteed behavior >> (17:19:50) nbjoerg: if for some strange reason you really need to enforce relative orders of global objects, put them in consecutively named sections > > Which appears to work. I tried this patch on top of yours: > > Not sure how this does with locality though. Hm, I'm not sure, but AFAIR some (all?) sections are aligned at 4K. Will this bring holes (4K-sizeof(struct sched_class)) in address space? > -- Steve > > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index e00f41aa8ec4..ff12a422ff19 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -108,6 +108,13 @@ > #define SBSS_MAIN .sbss > #endif > > +#define SCHED_DATA \ > + *(__idle_sched_class) \ > + *(__fair_sched_class) \ > + *(__rt_sched_class) \ > + *(__dl_sched_class) \ > + *(__stop_sched_class) > + > /* > * Align to a 32 byte boundary equal to the > * alignment gcc 4.5 uses for a struct > @@ -308,6 +315,7 @@ > #define DATA_DATA \ > *(.xiptext) \ > *(DATA_MAIN) \ > + SCHED_DATA \ > *(.ref.data) \ > *(.data..shared_aligned) /* percpu related */ \ > MEM_KEEP(init.data*) \ > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 43323f875cb9..5abdbe569f93 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2428,7 +2428,8 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p, > } > } > > -const struct sched_class dl_sched_class = { > +const struct sched_class dl_sched_class > + __attribute__((section("__dl_sched_class"))) = { > .next = &rt_sched_class, > .enqueue_task = enqueue_task_dl, > .dequeue_task = dequeue_task_dl, > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 08a233e97a01..e745fe0e0cd3 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -10745,7 +10745,8 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task > /* > * All the scheduling class methods: > */ > -const struct sched_class fair_sched_class = { > +const struct sched_class fair_sched_class > + __attribute__((section("__fair_sched_class"))) = { > .next = &idle_sched_class, > .enqueue_task = enqueue_task_fair, > .dequeue_task = dequeue_task_fair, > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index ffa959e91227..700a9c826f0e 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -454,7 +454,8 @@ static void update_curr_idle(struct rq *rq) > /* > * Simple, special scheduling class for the per-CPU idle tasks: > */ > -const struct sched_class idle_sched_class = { > +const struct sched_class idle_sched_class > + __attribute__((section("__idle_sched_class"))) = { > /* .next is NULL */ > /* no enqueue/yield_task for idle tasks */ > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index e591d40fd645..5d3f9bcddaeb 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -2354,7 +2354,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task) > return 0; > } > > -const struct sched_class rt_sched_class = { > +const struct sched_class rt_sched_class > + __attribute__((section("__rt_sched_class"))) = { > .next = &fair_sched_class, > .enqueue_task = enqueue_task_rt, > .dequeue_task = dequeue_task_rt, > diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c > index 4c9e9975684f..03bc7530ff75 100644 > --- a/kernel/sched/stop_task.c > +++ b/kernel/sched/stop_task.c > @@ -115,7 +115,8 @@ static void update_curr_stop(struct rq *rq) > /* > * Simple, special scheduling class for the per-CPU stop tasks: > */ > -const struct sched_class stop_sched_class = { > +const struct sched_class stop_sched_class > + __attribute__((section("__stop_sched_class"))) = { > .next = &dl_sched_class, > > .enqueue_task = enqueue_task_stop, >