From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f179.google.com (mail-lb0-f179.google.com [209.85.217.179]) by kanga.kvack.org (Postfix) with ESMTP id 0B140900021 for ; Mon, 27 Oct 2014 17:06:59 -0400 (EDT) Received: by mail-lb0-f179.google.com with SMTP id w7so1873031lbi.38 for ; Mon, 27 Oct 2014 14:06:59 -0700 (PDT) Received: from mail.ud10.udmedia.de (ud10.udmedia.de. [194.117.254.50]) by mx.google.com with ESMTPS id t13si20631657lal.121.2014.10.27.14.06.57 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Oct 2014 14:06:58 -0700 (PDT) Date: Mon, 27 Oct 2014 22:06:56 +0100 From: Markus Trippelsdorf Subject: Re: isolate_freepages_block(): very high intermittent overhead Message-ID: <20141027210656.GC348@x4> References: <20141027204003.GB348@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141027204003.GB348@x4> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Vlastimil Babka On 2014.10.27 at 21:40 +0100, Markus Trippelsdorf wrote: > On my v3.18-rc2 kernel isolate_freepages_block() sometimes shows up very > high (>20%) in perf top during the configuration phase of software > builds. It increases build time considerably. > > Unfortunately the issue is not 100% reproducible, because it appears > only intermittently. And the symptoms vanish after a few minutes. > > I think the "mm, compaction" series from Vlastimil is to blame, but it's > hard to be sure when bisection doesn't work. Here is an example: Overhead Shared Object Symbol 59.12% [kernel] [k] isolate_freepages_block 4.75% [kernel] [k] amd_e400_idle 1.10% [kernel] [k] clear_page_c 0.89% [kernel] [k] get_pfnblock_flags_mask 0.64% ld-2.19.90.so [.] do_lookup_x 0.64% [kernel] [k] unmap_single_vma 0.58% [kernel] [k] copy_page_rep 0.54% libc-2.19.90.so [.] memcpy@@GLIBC_2.14 0.52% [kernel] [k] filemap_map_pages 0.47% [kernel] [k] _cond_resched -- Markus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org