Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753298AbdHQQZL (ORCPT ); Thu, 17 Aug 2017 12:25:11 -0400 Received: from mail-oi0-f50.google.com ([209.85.218.50]:35013 "EHLO mail-oi0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752647AbdHQQZJ (ORCPT ); Thu, 17 Aug 2017 12:25:09 -0400 MIME-Version: 1.0 In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F07753786CE9@SHSMSX103.ccr.corp.intel.com> References: <84c7f26182b7f4723c0fe3b34ba912a9de92b8b7.1502758114.git.tim.c.chen@linux.intel.com> <37D7C6CF3E00A74B8858931C1DB2F07753786CE9@SHSMSX103.ccr.corp.intel.com> From: Linus Torvalds Date: Thu, 17 Aug 2017 09:25:08 -0700 X-Google-Sender-Auth: 5r2crOQliwjARr2w3bdOKPXgamk Message-ID: Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk To: "Liang, Kan" Cc: Tim Chen , Peter Zijlstra , 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: 692 Lines: 19 On Thu, Aug 17, 2017 at 9:17 AM, Liang, Kan wrote: > > We tried both 12 and 16 bit table and that didn't make a difference. > The long wake ups are mostly on the same page when we do instrumentation Ok. > Here is the wake_up_page_bit call stack when the workaround is running, which > is collected by perf record -g -a -e probe:wake_up_page_bit -- sleep 10 It's actually not really wake_up_page_bit() that is all that interesting, it would be more interesting to see which path it is that *adds* the entries. So it's mainly wait_on_page_bit_common(), but also add_page_wait_queue(). Can you get that call stack instead (or in addition to)? Linus