From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id E9A136B0069 for ; Fri, 9 Dec 2016 14:40:29 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id m203so8625235wma.2 for ; Fri, 09 Dec 2016 11:40:29 -0800 (PST) Received: from outbound-smtp09.blacknight.com (outbound-smtp09.blacknight.com. [46.22.139.14]) by mx.google.com with ESMTPS id d7si35309449wjf.81.2016.12.09.11.40.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Dec 2016 11:40:28 -0800 (PST) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp09.blacknight.com (Postfix) with ESMTPS id 3A5921C2CFF for ; Fri, 9 Dec 2016 19:40:28 +0000 (GMT) Date: Fri, 9 Dec 2016 19:40:27 +0000 From: Mel Gorman Subject: Re: [PATCH 1/2] mm, page_alloc: don't convert pfn to idx when merging Message-ID: <20161209194027.4ltdedctw2fshuwe@techsingularity.net> References: <20161209093754.3515-1-vbabka@suse.cz> <20161209172658.uebsgt5ju6gtz2bu@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Michal Hocko , "Kirill A. Shutemov" , Johannes Weiner On Fri, Dec 09, 2016 at 07:32:22PM +0100, Vlastimil Babka wrote: > > As a slight aside, I recently spotted that one of the largest overhead > > in the bulk free path was in the page_is_buddy() checks so pretty much > > anything that helps that is welcome. > > Interesting, the function shouldn't be doing really much on x86 without > debug config options? We might try further optimize the zone equivalence > checks, perhaps? I don't have the data any more but IIRC, it was cache miss intensive and I assumed at the time that it was checking cache cold struct pages during merges. At the time I was looking at splitting the per-cpu lists into irq and non-irq so wasn't focused on the page_is_buddy part of the profile. It just stuck in my mind as being surprisingly high. -- Mel Gorman SUSE Labs -- 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