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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 558F4C4363D for ; Fri, 2 Oct 2020 14:20:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0122A206A5 for ; Fri, 2 Oct 2020 14:20:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="aaN8GMeU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388068AbgJBOUl (ORCPT ); Fri, 2 Oct 2020 10:20:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726017AbgJBOUl (ORCPT ); Fri, 2 Oct 2020 10:20:41 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A905C0613D0 for ; Fri, 2 Oct 2020 07:20:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=G+5CbmqP20webr0ErY04CX5j7Q2Q2hOKTgJTeX7y+cg=; b=aaN8GMeUVBrvl3/4ybS46KAtE9 4Nuv+ycORy19ok5apyzZG0RmaMCChTsLiODaFsCek6iPU1ZtNN4+XioetNyj9KqRQ0/WeOJpivgVL qdw8f2vuAQiLEhpPQ6oXO0L5+BCNFdp2ExXVZJl1tZEO0piSRmoX3K39dAGJw4QVniI7przFa+cnl V7V+i2hoVxp7gk0Y1MFKy8k0ql1pPOaLs+Ig4esBfi2iAp1IMXohfplq6tLF/GmiXUS06+JqL8RYs H5TsnwUdeaPCUO8O9r/a8RRXIQaM1GAkI1VODe4H0vof+lxitiPpApFljeBYIpDa2la8qkSG76xx+ HpGT76bQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kOLvC-0002WE-5g; Fri, 02 Oct 2020 14:20:30 +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 894D4304B92; Fri, 2 Oct 2020 16:20:28 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 76539203A8F67; Fri, 2 Oct 2020 16:20:28 +0200 (CEST) Date: Fri, 2 Oct 2020 16:20:28 +0200 From: Peter Zijlstra To: Dietmar Eggemann Cc: tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de, qais.yousef@arm.com, swood@redhat.com, valentin.schneider@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vincent.donnefort@arm.com Subject: Re: [PATCH 3/9] sched/hotplug: Ensure only per-cpu kthreads run during hotplug Message-ID: <20201002142028.GY2628@hirez.programming.kicks-ass.net> References: <20200921163557.234036895@infradead.org> <20200921163845.520504267@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 25, 2020 at 06:38:50PM +0200, Dietmar Eggemann wrote: > On 21/09/2020 18:36, Peter Zijlstra wrote: > > [...] > > > This replaces the unlikely(rq->balance_callbacks) test at the tail of > > context_switch with an unlikely(rq->balance_work), the fast path is > > While looking for why BALANCE_WORK is needed: > > Shouldn't this be unlikely(rq->balance_callback) and > unlikely(rq->balance_flags)? But then we have two loads in the fastpath..