From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f44.google.com (mail-pb0-f44.google.com [209.85.160.44]) by kanga.kvack.org (Postfix) with ESMTP id 63FB86B0037 for ; Fri, 1 Nov 2013 16:38:38 -0400 (EDT) Received: by mail-pb0-f44.google.com with SMTP id rp16so4742880pbb.17 for ; Fri, 01 Nov 2013 13:38:37 -0700 (PDT) Received: from psmtp.com ([74.125.245.153]) by mx.google.com with SMTP id mi5si5682993pab.193.2013.11.01.13.38.36 for ; Fri, 01 Nov 2013 13:38:37 -0700 (PDT) Received: by mail-qe0-f53.google.com with SMTP id cy11so2879973qeb.26 for ; Fri, 01 Nov 2013 13:38:35 -0700 (PDT) Message-ID: <5274114B.7010302@gmail.com> Date: Fri, 01 Nov 2013 16:38:35 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH] mm: cache largest vma References: <1383337039.2653.18.camel@buesod1.americas.hpqcorp.net> In-Reply-To: <1383337039.2653.18.camel@buesod1.americas.hpqcorp.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso , Andrew Morton Cc: kosaki.motohiro@gmail.com, Hugh Dickins , Michel Lespinasse , Ingo Molnar , Mel Gorman , Rik van Riel , Guan Xuetao , aswin@hp.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org (11/1/13 4:17 PM), Davidlohr Bueso wrote: > While caching the last used vma already does a nice job avoiding > having to iterate the rbtree in find_vma, we can improve. After > studying the hit rate on a load of workloads and environments, > it was seen that it was around 45-50% - constant for a standard > desktop system (gnome3 + evolution + firefox + a few xterms), > and multiple java related workloads (including Hadoop/terasort), > and aim7, which indicates it's better than the 35% value documented > in the code. > > By also caching the largest vma, that is, the one that contains > most addresses, there is a steady 10-15% hit rate gain, putting > it above the 60% region. This improvement comes at a very low > overhead for a miss. Furthermore, systems with !CONFIG_MMU keep > the current logic. I'm slightly surprised this cache makes 15% hit. Which application get a benefit? You listed a lot of applications, but I'm not sure which is highly depending on largest vma. -- 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