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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 6AA17C2BB55 for ; Thu, 16 Apr 2020 11:12:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4527A206E9 for ; Thu, 16 Apr 2020 11:12:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="yhehKYns" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2506261AbgDPLMC (ORCPT ); Thu, 16 Apr 2020 07:12:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2506032AbgDPLEr (ORCPT ); Thu, 16 Apr 2020 07:04:47 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 926FDC03C1A9 for ; Thu, 16 Apr 2020 03:47:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; 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=uT2ucy3qx5aL2WVYyVl5nm3yhCGAKoXW4NTEdyzjdRI=; b=yhehKYnstqda4PzxJiK7i/0lWu FF4DXLsczqcjq6INSj8GeFF/bI1by+iDATbLPlhasSlC/i2I1U979VDslg9hen6Upv4wpp8krz1dV +Y6thdzQnF+5m3sKbJCGZYdgwe9zXByT161HaFQp20VHeOiNOAcRohajcWBxATtD/DIEpBF46pGh5 q4CQIZXdqBY/PwC2QeMWQ1SDg5PaqouC24SXFtL6t6g/RUTLtx7+M3F2qJnxhoCL+kvwZc/ZV4fSc UgiulBR+vG07XElyQmY3D2ghaMHRDQiZ0vMd2RITGXIRdAnnXk29KDm79Fv6sUMs7Kzx0qV556R8b G7tat/MA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jP23N-0005D0-HG; Thu, 16 Apr 2020 10:47:29 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 13440307005; Thu, 16 Apr 2020 12:47:25 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E597B2B0DC738; Thu, 16 Apr 2020 12:47:25 +0200 (CEST) Date: Thu, 16 Apr 2020 12:47:25 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: Valentin Schneider , linux-kernel , Ingo Molnar , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Steven Rostedt Subject: Re: [PATCH v3 6/9] sched: Kill select_task_rq()'s sd_flag parameter Message-ID: <20200416104725.GM20730@hirez.programming.kicks-ass.net> References: <20200415210512.805-1-valentin.schneider@arm.com> <20200415210512.805-7-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 16, 2020 at 09:42:36AM +0200, Vincent Guittot wrote: > On Wed, 15 Apr 2020 at 23:05, Valentin Schneider > > @@ -6622,13 +6622,25 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > > * preempt must be disabled. > > */ > > static int > > +select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) > > { > > + int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING); > > struct sched_domain *tmp, *sd = NULL; > > int cpu = smp_processor_id(); > > int new_cpu = prev_cpu; > > int want_affine = 0; > > - int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING); > > + int sd_flag; > > + > > + switch (wake_flags & (WF_TTWU | WF_FORK | WF_EXEC)) { > > You remove a function parameter, which was directly set with the right > flag, but then you add a switch case to recreate this sd_flag > internally. Not sure we can say that it's real benefit > > > + case WF_TTWU: > > + sd_flag = SD_BALANCE_WAKE; > > + break; > > + case WF_FORK: > > + sd_flag = SD_BALANCE_FORK; > > + break; > > + default: > > + sd_flag = SD_BALANCE_EXEC; > > + } Agreed, that's a bit yuck, how about something like so instead: --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -11,10 +11,12 @@ */ #ifdef CONFIG_SMP +/* First nibble of SD_flag is shared with WF_flag */ #define SD_BALANCE_NEWIDLE 0x0001 /* Balance when about to become idle */ #define SD_BALANCE_EXEC 0x0002 /* Balance on exec */ #define SD_BALANCE_FORK 0x0004 /* Balance on fork, clone */ #define SD_BALANCE_WAKE 0x0008 /* Balance on wakeup */ + #define SD_WAKE_AFFINE 0x0010 /* Wake task to waking CPU */ #define SD_ASYM_CPUCAPACITY 0x0020 /* Domain members have different CPU capacities */ #define SD_SHARE_CPUCAPACITY 0x0040 /* Domain members share CPU capacity */ --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6635,16 +6635,8 @@ select_task_rq_fair(struct task_struct * int want_affine = 0; int sd_flag; - switch (wake_flags & (WF_TTWU | WF_FORK | WF_EXEC)) { - case WF_TTWU: - sd_flag = SD_BALANCE_WAKE; - break; - case WF_FORK: - sd_flag = SD_BALANCE_FORK; - break; - default: - sd_flag = SD_BALANCE_EXEC; - } + /* SD_flags and WF_flags share the first nibble */ + sd_flag = wake_flags & 0xf; if (sd_flag & SD_BALANCE_WAKE) { record_wakee(p); --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1685,11 +1685,12 @@ static inline int task_on_rq_migrating(s /* * Wake flags */ -#define WF_SYNC 0x01 /* Waker goes to sleep after wakeup */ -#define WF_TTWU 0x02 /* Regular task wakeup */ -#define WF_FORK 0x04 /* Child wakeup after fork */ -#define WF_EXEC 0x08 /* "Fake" wakeup at exec */ -#define WF_MIGRATED 0x10 /* Internal use, task got migrated */ +#define WF_EXEC 0x02 /* SD_BALANCE_EXEC */ +#define WF_FORK 0x04 /* SD_BALANCE_FORK */ +#define WF_TTWU 0x08 /* SD_BALANCE_WAKE */ + +#define WF_SYNC 0x10 /* Waker goes to sleep after wakeup */ +#define WF_MIGRATED 0x20 /* Internal use, task got migrated */ /* * To aid in avoiding the subversion of "niceness" due to uneven distribution