Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752237AbdHVU7C (ORCPT ); Tue, 22 Aug 2017 16:59:02 -0400 Received: from mail-oi0-f49.google.com ([209.85.218.49]:34495 "EHLO mail-oi0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751887AbdHVU7B (ORCPT ); Tue, 22 Aug 2017 16:59:01 -0400 MIME-Version: 1.0 In-Reply-To: <20170822205316.GS32112@worktop.programming.kicks-ass.net> References: <37D7C6CF3E00A74B8858931C1DB2F07753787AE4@SHSMSX103.ccr.corp.intel.com> <20170818185455.qol3st2nynfa47yc@techsingularity.net> <20170821183234.kzennaaw2zt2rbwz@techsingularity.net> <37D7C6CF3E00A74B8858931C1DB2F07753788B58@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378A24A@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378A377@SHSMSX103.ccr.corp.intel.com> <20170822205316.GS32112@worktop.programming.kicks-ass.net> From: Linus Torvalds Date: Tue, 22 Aug 2017 13:58:59 -0700 X-Google-Sender-Auth: Cqa8EKU0C8q9z9nI5o4NI_iPUHw Message-ID: Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk To: Peter Zijlstra Cc: "Liang, Kan" , Mel Gorman , Mel Gorman , "Kirill A. Shutemov" , Tim Chen , Ingo Molnar , Andi Kleen , Andrew Morton , Johannes Weiner , Jan Kara , linux-mm , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 491 Lines: 13 On Tue, Aug 22, 2017 at 1:53 PM, Peter Zijlstra wrote: > > So _the_ problem with yield() is when you hit this with a RT task it > will busy spin and possibly not allow the task that actually has the > lock to make progress at all. I thought we had explicitly defined yield() to not do that. But I guess we could make this yielding behavior depend on a few more heuristics. So do the yield only when there is contention, and when it's a non-RT task. Linus