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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 5946BC433ED for ; Wed, 14 Apr 2021 17:10:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D18D6117A for ; Wed, 14 Apr 2021 17:10:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237646AbhDNRLI (ORCPT ); Wed, 14 Apr 2021 13:11:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:40220 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233673AbhDNRLH (ORCPT ); Wed, 14 Apr 2021 13:11:07 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EBDBBB0DA; Wed, 14 Apr 2021 17:10:44 +0000 (UTC) Subject: Re: [PATCH 06/11] mm/page_alloc: Reduce duration that IRQs are disabled for VM counters To: Mel Gorman , Linux-MM , Linux-RT-Users Cc: LKML , Chuck Lever , Jesper Dangaard Brouer , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Michal Hocko References: <20210414133931.4555-1-mgorman@techsingularity.net> <20210414133931.4555-7-mgorman@techsingularity.net> From: Vlastimil Babka Message-ID: Date: Wed, 14 Apr 2021 19:10:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210414133931.4555-7-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/14/21 3:39 PM, Mel Gorman wrote: > IRQs are left disabled for the zone and node VM event counters. This is > unnecessary as the affected counters are allowed to race for preemmption > and IRQs. > > This patch reduces the scope of IRQs being disabled > via local_[lock|unlock]_irq on !PREEMPT_RT kernels. One > __mod_zone_freepage_state is still called with IRQs disabled. While this > could be moved out, it's not free on all architectures as some require > IRQs to be disabled for mod_zone_page_state on !PREEMPT_RT kernels. > > Signed-off-by: Mel Gorman Nice! Acked-by: Vlastimil Babka > --- > mm/page_alloc.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cff0f1c98b28..295624fe293b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3474,11 +3474,11 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone, > pcp = this_cpu_ptr(zone->per_cpu_pageset); > list = &pcp->lists[migratetype]; > page = __rmqueue_pcplist(zone, migratetype, alloc_flags, pcp, list); > + local_unlock_irqrestore(&pagesets.lock, flags); > if (page) { > __count_zid_vm_events(PGALLOC, page_zonenum(page), 1); > zone_statistics(preferred_zone, zone, 1); > } > - local_unlock_irqrestore(&pagesets.lock, flags); > return page; > } > > @@ -3530,15 +3530,15 @@ struct page *rmqueue(struct zone *preferred_zone, > if (!page) > page = __rmqueue(zone, order, migratetype, alloc_flags); > } while (page && check_new_pages(page, order)); > - spin_unlock(&zone->lock); > if (!page) > goto failed; > + > __mod_zone_freepage_state(zone, -(1 << order), > get_pcppage_migratetype(page)); > + spin_unlock_irqrestore(&zone->lock, flags); > > __count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order); > zone_statistics(preferred_zone, zone, 1); > - local_irq_restore(flags); > > out: > /* Separate test+clear to avoid unnecessary atomics */ > @@ -3551,7 +3551,7 @@ struct page *rmqueue(struct zone *preferred_zone, > return page; > > failed: > - local_irq_restore(flags); > + spin_unlock_irqrestore(&zone->lock, flags); > return NULL; > } > > @@ -5103,11 +5103,11 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, > nr_populated++; > } > > + local_unlock_irqrestore(&pagesets.lock, flags); > + > __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account); > zone_statistics(ac.preferred_zoneref->zone, zone, nr_account); > > - local_unlock_irqrestore(&pagesets.lock, flags); > - > return nr_populated; > > failed_irq: >