From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751611AbeBBFU6 (ORCPT ); Fri, 2 Feb 2018 00:20:58 -0500 Received: from mga04.intel.com ([192.55.52.120]:12406 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751463AbeBBFUp (ORCPT ); Fri, 2 Feb 2018 00:20:45 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,447,1511856000"; d="scan'208";a="200747805" Date: Fri, 2 Feb 2018 13:21:20 +0800 From: Aaron Lu To: daniel.m.jordan@oracle.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, ak@linux.intel.com, akpm@linux-foundation.org, Dave.Dice@oracle.com, dave@stgolabs.net, khandual@linux.vnet.ibm.com, ldufour@linux.vnet.ibm.com, mgorman@suse.de, mhocko@kernel.org, pasha.tatashin@oracle.com, steven.sistare@oracle.com, yossi.lev@oracle.com, Dave Hansen , Tim Chen Subject: Re: [RFC PATCH v1 13/13] mm: splice local lists onto the front of the LRU Message-ID: <20180202052120.GA16272@intel.com> References: <20180131230413.27653-1-daniel.m.jordan@oracle.com> <20180131230413.27653-14-daniel.m.jordan@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180131230413.27653-14-daniel.m.jordan@oracle.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 31, 2018 at 06:04:13PM -0500, daniel.m.jordan@oracle.com wrote: > Now that release_pages is scaling better with concurrent removals from > the LRU, the performance results (included below) showed increased > contention on lru_lock in the add-to-LRU path. > > To alleviate some of this contention, do more work outside the LRU lock. > Prepare a local list of pages to be spliced onto the front of the LRU, > including setting PageLRU in each page, before taking lru_lock. Since > other threads use this page flag in certain checks outside lru_lock, > ensure each page's LRU links have been properly initialized before > setting the flag, and use memory barriers accordingly. > > Performance Results > > This is a will-it-scale run of page_fault1 using 4 different kernels. > > kernel kern # > > 4.15-rc2 1 > large-zone-batch 2 > lru-lock-base 3 > lru-lock-splice 4 > > Each kernel builds on the last. The first is a baseline, the second > makes zone->lock more scalable by increasing an order-0 per-cpu > pagelist's 'batch' and 'high' values to 310 and 1860 respectively Since the purpose of the patchset is to optimize lru_lock, you may consider adjusting pcp->high to be >= 32768(page_fault1's test size is 128M = 32768 pages). That should eliminate zone->lock contention entirely. > (courtesy of Aaron Lu's patch), the third scales lru_lock without > splicing pages (the previous patch in this series), and the fourth adds > page splicing (this patch). > > N tasks mmap, fault, and munmap anonymous pages in a loop until the test > time has elapsed.