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=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 00BD6C433E0 for ; Wed, 31 Mar 2021 08:18:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C10B8619D8 for ; Wed, 31 Mar 2021 08:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234229AbhCaISQ (ORCPT ); Wed, 31 Mar 2021 04:18:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45917 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234197AbhCaIRy (ORCPT ); Wed, 31 Mar 2021 04:17:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617178672; 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=3bTqLjMGBkNyk6LPfhvftRY7GVRzCJFKJwpWtZQvrdY=; b=bxq8/UeN840xD8FxtBJr/6TeZjv63MefU0pkHwOhreGopYAL7hv1mjBogRHAlAtDO4u3MV vCcIY0EoOcXmYSeee9dz4E0QiPxAN8osEItTuELSPdvarTYJDMCqxI2s1fHHZJxNDk3/nV rdgPHD4IO6Bn9gYJ+41+kRcAYVxxb4I= 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-501-vV6X7zIlNfaW18iSYhKvUA-1; Wed, 31 Mar 2021 04:17:48 -0400 X-MC-Unique: vV6X7zIlNfaW18iSYhKvUA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E33BB8710FD; Wed, 31 Mar 2021 08:17:45 +0000 (UTC) Received: from carbon (unknown [10.36.110.5]) by smtp.corp.redhat.com (Postfix) with ESMTP id 597E46A900; Wed, 31 Mar 2021 08:17:40 +0000 (UTC) Date: Wed, 31 Mar 2021 10:17:39 +0200 From: Jesper Dangaard Brouer To: Mel Gorman Cc: Linux-MM , Linux-RT-Users , LKML , Chuck Lever , Matthew Wilcox , brouer@redhat.com Subject: Re: [RFC PATCH 0/6] Use local_lock for pcp protection and reduce stat overhead Message-ID: <20210331101739.0cc3630e@carbon> In-Reply-To: <20210331073805.GY3697@techsingularity.net> References: <20210329120648.19040-1-mgorman@techsingularity.net> <20210330205154.1fe1e479@carbon> <20210331073805.GY3697@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Wed, 31 Mar 2021 08:38:05 +0100 Mel Gorman wrote: > On Tue, Mar 30, 2021 at 08:51:54PM +0200, Jesper Dangaard Brouer wrote: > > On Mon, 29 Mar 2021 13:06:42 +0100 > > Mel Gorman wrote: > > > > > This series requires patches in Andrew's tree so the series is also > > > available at > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-percpu-local_lock-v1r15 > > > > > > tldr: Jesper and Chuck, it would be nice to verify if this series helps > > > the allocation rate of the bulk page allocator. RT people, this > > > *partially* addresses some problems PREEMPT_RT has with the page > > > allocator but it needs review. > > > > I've run a new micro-benchmark[1] which shows: > > (CPU: Intel(R) Xeon(R) CPU E5-1650 v4 @ 3.60GHz) > > > > > > BASELINE > > single_page alloc+put: 194 cycles(tsc) 54.106 ns > > > > ARRAY variant: time_bulk_page_alloc_free_array: step=bulk size > > > > Per elem: 195 cycles(tsc) 54.225 ns (step:1) > > Per elem: 127 cycles(tsc) 35.492 ns (step:2) > > Per elem: 117 cycles(tsc) 32.643 ns (step:3) > > Per elem: 111 cycles(tsc) 30.992 ns (step:4) > > Per elem: 106 cycles(tsc) 29.606 ns (step:8) > > Per elem: 102 cycles(tsc) 28.532 ns (step:16) > > Per elem: 99 cycles(tsc) 27.728 ns (step:32) > > Per elem: 98 cycles(tsc) 27.252 ns (step:64) > > Per elem: 97 cycles(tsc) 27.090 ns (step:128) > > > > This should be seen in comparison with the older micro-benchmark[2] > > done on branch mm-bulk-rebase-v5r9. > > > > BASELINE > > single_page alloc+put: Per elem: 199 cycles(tsc) 55.472 ns > > > > ARRAY variant: time_bulk_page_alloc_free_array: step=bulk size > > > > Per elem: 202 cycles(tsc) 56.383 ns (step:1) > > Per elem: 144 cycles(tsc) 40.047 ns (step:2) > > Per elem: 134 cycles(tsc) 37.339 ns (step:3) > > Per elem: 128 cycles(tsc) 35.578 ns (step:4) > > Per elem: 120 cycles(tsc) 33.592 ns (step:8) > > Per elem: 116 cycles(tsc) 32.362 ns (step:16) > > Per elem: 113 cycles(tsc) 31.476 ns (step:32) > > Per elem: 110 cycles(tsc) 30.633 ns (step:64) > > Per elem: 110 cycles(tsc) 30.596 ns (step:128) > > > > Ok, so bulk allocation is faster than allocating single pages, no surprise > there. Putting the array figures for bulk allocation into tabular format > and comparing we get; > > Array variant (time to allocate a page in nanoseconds, lower is better) > Baseline Patched > 1 56.383 54.225 (+3.83%) > 2 40.047 35.492 (+11.38%) > 3 37.339 32.643 (+12.58%) > 4 35.578 30.992 (+12.89%) > 8 33.592 29.606 (+11.87%) > 16 32.362 28.532 (+11.85%) > 32 31.476 27.728 (+11.91%) > 64 30.633 27.252 (+11.04%) > 128 30.596 27.090 (+11.46%) > > The series is 11-12% faster when allocating multiple pages. That's a > fairly positive outcome and I'll include this in the series leader if > you have no objections. That is fine by me to add this to the cover letter. I like your tabular format as it makes is easier to compare. If you use the nanosec measurements and not the cycles, you should state that this was run on a CPU E5-1650 v4 @ 3.60GHz. You might notice that the factor between cycles(tsc) and ns is very close to 3.6. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer