From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21446C3A5A1 for ; Wed, 28 Aug 2019 08:28:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F077720828 for ; Wed, 28 Aug 2019 08:28:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726439AbfH1I2C (ORCPT ); Wed, 28 Aug 2019 04:28:02 -0400 Received: from mga12.intel.com ([192.55.52.136]:33769 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726253AbfH1I2C (ORCPT ); Wed, 28 Aug 2019 04:28:02 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Aug 2019 01:28:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,440,1559545200"; d="scan'208";a="210081623" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga002.fm.intel.com with ESMTP; 28 Aug 2019 01:28:00 -0700 Date: Wed, 28 Aug 2019 16:27:38 +0800 From: Wei Yang To: Vlastimil Babka Cc: Wei Yang , akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matthew Wilcox Subject: Re: [RESEND [PATCH] 0/2] mm/mmap.c: reduce subtree gap propagation a little Message-ID: <20190828082738.GA20183@richard> Reply-To: Wei Yang References: <20190828060614.19535-1-richardw.yang@linux.intel.com> <4503e006-76ba-ed06-0184-6e361a66ba88@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4503e006-76ba-ed06-0184-6e361a66ba88@suse.cz> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 28, 2019 at 10:01:40AM +0200, Vlastimil Babka wrote: >On 8/28/19 8:06 AM, Wei Yang wrote: >> When insert and delete a vma, it will compute and propagate related subtree >> gap. After some investigation, we can reduce subtree gap propagation a little. >> >> [1]: This one reduce the propagation by update *next* gap after itself, since >> *next* must be a parent in this case. >> [2]: This one achieve this by unlinking vma from list. >> >> After applying these two patches, test shows it reduce 0.3% function call for >> vma_compute_subtree_gap. > >BTW, what's the overall motivation of focusing so much >micro-optimization effort on the vma tree lately? This has been rather >stable code where we can be reasonably sure of all bugs being found. Now >even after some review effort, subtle bugs can be introduced. And >Matthew was warning for a while about an upcoming major rewrite of the >whole data structure, which will undo all this effort? > Hi, Vlastimil Thanks for your comment. I just found there could be some refine for the code and then I modify and test it. Hope this could help a little. You concern is valid. The benefits / cost may be not that impressive. The community have the final decision. For me, I just want to make it better if we can. -- Wei Yang Help you, Help me