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=-21.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 745B6C433E0 for ; Tue, 23 Mar 2021 15:09:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37B8C619BD for ; Tue, 23 Mar 2021 15:09:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232700AbhCWPIx (ORCPT ); Tue, 23 Mar 2021 11:08:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51832 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232689AbhCWPI2 (ORCPT ); Tue, 23 Mar 2021 11:08:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616512108; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7Dk+kTaXIBxkfJmBKu6XikBMXUgoktdgDa5FmOR121g=; b=DCNnizOGr1mD3hmIQ2ADe1YeF5+vIzvH8jwPoLCMwmeMr6ZvzVesjeVKWk1NGZcQ9BWOG/ OqzlrGDlFvR+WGQcnnvIg9MvNvxTuUJLODjA1qNAg7XwzU3zb4u3tv1WQJZlUc3VvPc8c4 wZ8BAES5PqAF3M7HxQXFwSegxPWlGWI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-201-d0GLNY50MHKwkdaeWWEmNA-1; Tue, 23 Mar 2021 11:08:23 -0400 X-MC-Unique: d0GLNY50MHKwkdaeWWEmNA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BD5B4612A1; Tue, 23 Mar 2021 15:08:21 +0000 (UTC) Received: from carbon (unknown [10.36.110.5]) by smtp.corp.redhat.com (Postfix) with ESMTP id 69805196E3; Tue, 23 Mar 2021 15:08:15 +0000 (UTC) Date: Tue, 23 Mar 2021 16:08:14 +0100 From: Jesper Dangaard Brouer To: Mel Gorman Cc: Chuck Lever , Vlastimil Babka , Andrew Morton , Christoph Hellwig , Alexander Duyck , Matthew Wilcox , LKML , Linux-Net , Linux-MM , Linux-NFS , brouer@redhat.com Subject: Re: [PATCH 0/3 v5] Introduce a bulk order-0 page allocator Message-ID: <20210323160814.62a248fb@carbon> In-Reply-To: <20210323104421.GK3697@techsingularity.net> References: <20210322091845.16437-1-mgorman@techsingularity.net> <20210323104421.GK3697@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 23 Mar 2021 10:44:21 +0000 Mel Gorman wrote: > On Mon, Mar 22, 2021 at 09:18:42AM +0000, Mel Gorman wrote: > > This series is based on top of Matthew Wilcox's series "Rationalise > > __alloc_pages wrapper" and does not apply to 5.12-rc2. If you want to > > test and are not using Andrew's tree as a baseline, I suggest using the > > following git tree > > > > git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-bulk-rebase-v5r9 > > > > Jesper and Chuck, would you mind rebasing on top of the following branch > please? > > git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-bulk-rebase-v6r2 > > The interface is the same so the rebase should be trivial. > > Jesper, I'm hoping you see no differences in performance but it's best > to check. I will rebase and check again. The current performance tests that I'm running, I observe that the compiler layout the code in unfortunate ways, which cause I-cache performance issues. I wonder if you could integrate below patch with your patchset? (just squash it) -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer [PATCH] mm: optimize code layout for __alloc_pages_bulk From: Jesper Dangaard Brouer Looking at perf-report and ASM-code for __alloc_pages_bulk() then the code activated is suboptimal. The compiler guess wrong and place unlikely code in the beginning. Due to the use of WARN_ON_ONCE() macro the UD2 asm instruction is added to the code, which confuse the I-cache prefetcher in the CPU Signed-off-by: Jesper Dangaard Brouer --- mm/page_alloc.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f60f51a97a7b..88a5c1ce5b87 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5003,10 +5003,10 @@ int __alloc_pages_bulk(gfp_t gfp, int preferred_nid, unsigned int alloc_flags; int nr_populated = 0, prep_index = 0; - if (WARN_ON_ONCE(nr_pages <= 0)) + if (unlikely(nr_pages <= 0)) return 0; - if (WARN_ON_ONCE(page_list && !list_empty(page_list))) + if (unlikely(page_list && !list_empty(page_list))) return 0; /* Skip populated array elements. */ @@ -5018,7 +5018,7 @@ int __alloc_pages_bulk(gfp_t gfp, int preferred_nid, prep_index = nr_populated; } - if (nr_pages == 1) + if (unlikely(nr_pages == 1)) goto failed; /* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */ @@ -5054,7 +5054,7 @@ int __alloc_pages_bulk(gfp_t gfp, int preferred_nid, * If there are no allowed local zones that meets the watermarks then * try to allocate a single page and reclaim if necessary. */ - if (!zone) + if (unlikely(!zone)) goto failed; /* Attempt the batch allocation */ @@ -5075,7 +5075,7 @@ int __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page = __rmqueue_pcplist(zone, ac.migratetype, alloc_flags, pcp, pcp_list); - if (!page) { + if (unlikely(!page)) { /* Try and get at least one page */ if (!nr_populated) goto failed_irq;