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 79B8EC2D0A8 for ; Wed, 23 Sep 2020 17:08:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0733C20C09 for ; Wed, 23 Sep 2020 17:08:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZcAKUHA3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726714AbgIWRI1 (ORCPT ); Wed, 23 Sep 2020 13:08:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726405AbgIWRI1 (ORCPT ); Wed, 23 Sep 2020 13:08:27 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54170C0613CE for ; Wed, 23 Sep 2020 10:08:27 -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=sxnYwak8DIWStnPUO/Jr70PPBMVMVI0+DKQ+9tS2nh0=; b=ZcAKUHA37509MGqZnOxOOsh3x1 rOnlrIrWYeM6uz6R2WpNkYbKBH0Fv+qMmsRNjH78xPpM5XuGqMW8TPINQMep/iQP4eE9mu6l8+7cb HsLRFpm8C53aUC/Iquw6UvDVvD+OU2ugQ84vDjd562FEGk5G9Ln56HdzFQ6dubGUfkY+Z4nQRdqzX Br7cw3FUY7a73fwiDf1jNnStsDo4gORvp4VR7+BgKg6MAoRJwhLAAKIoV1RLXBG/qQUelPaaLH9Qg YTyjncTWDBo+2st4pHpUqfdbpEB5uOY8q0TtWyYVu8MOxExGK9SCe2F3he525PJC7T/YD86PXkspZ 4AjDj2rw==; 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 1kL8FY-0001nQ-A4; Wed, 23 Sep 2020 17:08:12 +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 9C8CE3050F0; Wed, 23 Sep 2020 19:08:09 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 637A22B88AD30; Wed, 23 Sep 2020 19:08:09 +0200 (CEST) Date: Wed, 23 Sep 2020 19:08:09 +0200 From: peterz@infradead.org To: Thomas Gleixner Cc: Daniel Bristot de Oliveira , 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, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vincent.donnefort@arm.com Subject: Re: [PATCH 7/9] sched: Add migrate_disable() Message-ID: <20200923170809.GY1362448@hirez.programming.kicks-ass.net> References: <20200921163557.234036895@infradead.org> <20200921163845.769861942@infradead.org> <87v9g7aqjd.fsf@nanos.tec.linutronix.de> <86929eee-36da-93a5-5280-00e6df1ef496@redhat.com> <87v9g4ao8h.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v9g4ao8h.fsf@nanos.tec.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 23, 2020 at 10:31:10AM +0200, Thomas Gleixner wrote: > In practice migrate disable could be taken into account on placement > decisions, but yes we don't have anything like that at the moment. I think at the very least we should do some of that. The premise is wanting to run the M highest priority tasks, when a CPU drops priority, it tries to PULL a higher priority task towards itself. If this PULL selects a migrate_disable() tasks, it means the task is in the M highest prio tasks. Since obviously that task cannot get pulled, we should then pull the current running task of that CPU, this would then allow the migrate_disable() task to resume execution. I'll go try and cook up something along those lines...