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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33157C433F5 for ; Wed, 2 Feb 2022 14:14:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344802AbiBBOOm (ORCPT ); Wed, 2 Feb 2022 09:14:42 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:32692 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238344AbiBBOOj (ORCPT ); Wed, 2 Feb 2022 09:14:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643811279; 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=+y9K91m9QPPmsSsA5/klqliIs/9Sf25p3BHVEid1hDo=; b=iQHdzKqxAipmE1WWKVWBPPwmPi+IRe7tpfKTcoPcQoegaRdSWy3m2h/x+qR8VxWNiDiXLG 57yiefe/tbNFtz9q/q9/1Z0nmH0nwLNoE+EF8iFzCIIqyGo1/nu4PjcIHnL8NwV8m+I22g jtmntkjumaNHpp6Al30zWkf0j5zVjmk= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-15-kQaDXAu9PKOYsKYK5xtMLg-1; Wed, 02 Feb 2022 09:14:38 -0500 X-MC-Unique: kQaDXAu9PKOYsKYK5xtMLg-1 Received: by mail-ed1-f71.google.com with SMTP id ed6-20020a056402294600b004090fd8a936so10491171edb.23 for ; Wed, 02 Feb 2022 06:14:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:message-id:date:mime-version:user-agent:cc :subject:content-language:to:references:in-reply-to :content-transfer-encoding; bh=+y9K91m9QPPmsSsA5/klqliIs/9Sf25p3BHVEid1hDo=; b=m5eRKQBq/v2oYFFLxQ9KmVKHmbQCuz7s0f8wC04VpjrlspLETCUwFLXVZgQSjlqbli 7Aq+ebCdvS8Z8X0li3VEQh7GdUu10ZIEJ1eKaGEbFUj9Arr0oOXH2U9Mp1XYAEOlBpIb tJiyGcw8AnRkA03tPEjn+y5/kCzMxDdPQFJKUXFJvBScTWciQzKp+dC0YTQwcMET+Df8 t33nTUBz6yidpUDRhqKycwDIWnTRwktM7Q8FvmmZGGHH9QgfOEGd8iI52f9Q4uvhEF1r omDjt5rEBr7TnhhAt2d6xxwCwHdyGnfT9jDMLIG7+YCsh8EW58s25uu+ORDMq2SmKN8u oPWA== X-Gm-Message-State: AOAM533eH4JN5ShBphthscI3+4c7BtZex/z1V28kdF0A2elyX3STF8sP FWxPR1g9DiHF6TK5sqjupD/ubcubLJ41svUNLIdXQGE79aMZDHcmDIM/qkc8/ONhKtKxfGdlmyV OLW6SsfI6ny4VfZGP X-Received: by 2002:a05:6402:2549:: with SMTP id l9mr18123477edb.129.1643811276832; Wed, 02 Feb 2022 06:14:36 -0800 (PST) X-Google-Smtp-Source: ABdhPJzSFI26aBe2IhgXO34LeNPfVoyGqpKQ9C8YoCWumeQ9jX1kghuUM4Rx53FHT+MmU/KN8bf4Ng== X-Received: by 2002:a05:6402:2549:: with SMTP id l9mr18123458edb.129.1643811276644; Wed, 02 Feb 2022 06:14:36 -0800 (PST) Received: from [192.168.0.50] (87-59-106-155-cable.dk.customer.tdc.net. [87.59.106.155]) by smtp.gmail.com with ESMTPSA id az19sm6004307ejc.101.2022.02.02.06.14.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 02 Feb 2022 06:14:35 -0800 (PST) From: Jesper Dangaard Brouer X-Google-Original-From: Jesper Dangaard Brouer Message-ID: <1302c302-1a4b-ff0d-c989-cbe851c92e06@redhat.com> Date: Wed, 2 Feb 2022 15:14:34 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Cc: brouer@redhat.com, kuba@kernel.org, davem@davemloft.net, ilias.apalodimas@linaro.org, hawk@kernel.org, Tariq Toukan , Saeed Mahameed Subject: Re: [PATCH 1/6] net: page_pool: Add alloc stats and fast path stat Content-Language: en-US To: Joe Damato , netdev@vger.kernel.org References: <1643237300-44904-1-git-send-email-jdamato@fastly.com> <1643237300-44904-2-git-send-email-jdamato@fastly.com> In-Reply-To: <1643237300-44904-2-git-send-email-jdamato@fastly.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 26/01/2022 23.48, Joe Damato wrote: > @@ -86,6 +100,7 @@ struct page_pool_params { > > struct page_pool { > struct page_pool_params p; > + struct page_pool_stats ps; > > struct delayed_work release_dw; The placement of page_pool_stats is problematic, due to cache-line placement. It will be sharing a cache-line with page_pool_params, which is read-mostly. As I say on benchmark email, this is likely the performance regression you saw. I *do* know you have changed location (to percpu) in newer patch versions, but I think it is important to point out, that we have to be very careful about cache-line placements, and which part of 'struct page_pool' is accessed by which part of the code RX or DMA-TX-completion "return" code. --Jesper