From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Subject: Re: [PATCH v5 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Date: Mon, 27 Jun 2022 16:07:32 +0000 Message-ID: References: <20220606222058.86688-1-yosryahmed@google.com> <20220606222058.86688-2-yosryahmed@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=KXpJaULYCMOBvM0KZ+Y0QmYKcs5GsOT3UDoT12OxOmZTuofXiRwwGm/WgJTM1heXoI t1dv3k342OQnZ9iooXjd608cniWLl0qlDw2/EFrZO3JITiMUniSnoS9vRpsVYcQj8vN/ I7nko6H+yxfXlWmj6BpVmIQCvWqpF55RTmiG3dExwV8krl6JWA8dxuz7o3cuKUtlCKLL AUH1GrHaKcLi0AxNkq1Q0RlPIztx9SDq4ccjZXK7Aa2jkpBZXbRVUSJ+/fIBfJxIB9bo wqHrvEDbll+Qw87/iH2rzRcMOLCQ34VpKyfcZXoB0fUgM3GYU80A2xB80LHN6E80KQa1 5riQ== Content-Disposition: inline In-Reply-To: <20220606222058.86688-2-yosryahmed@google.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Yosry Ahmed Cc: Wanpeng Li , kvm@vger.kernel.org, Roman Gushchin , Michal Hocko , linux-mm@kvack.org, Zefan Li , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Joerg Roedel , Shakeel Butt , cgroups@vger.kernel.org, Andrew Morton , linux-arm-kernel@lists.infradead.org, Jim Mattson , linux-kernel@vger.kernel.org, Johannes Weiner , Tejun Heo , Paolo Bonzini , Vitaly Kuznetsov On Mon, Jun 06, 2022, Yosry Ahmed wrote: > Add NR_SECONDARY_PAGETABLE stat to count secondary page table uses, e.g. > KVM mmu. This provides more insights on the kernel memory used > by a workload. Please provide more justification for NR_SECONDARY_PAGETABLE in the changelog. Specially, answer the questions that were asked in the previous version: 1. Why not piggyback NR_PAGETABLE? 2. Why a "generic" NR_SECONDARY_PAGETABLE instead of NR_VIRT_PAGETABLE? It doesn't have to be super long, but provide enough info so that reviewers and future readers don't need to go spelunking to understand the motivation for the new counter type. And it's probably worth an explicit Link to Marc's question that prompted the long discussion in the previous version, that way if someone does want the gory details they have a link readily available. Link: https://lore.kernel.org/all/87ilqoi77b.wl-maz@kernel.org 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF7AAC433EF for ; Mon, 27 Jun 2022 16:07:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5CC7B4B2BC; Mon, 27 Jun 2022 12:07:41 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 16vmEODqd7ah; Mon, 27 Jun 2022 12:07:40 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 542384B29E; Mon, 27 Jun 2022 12:07:40 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 902BF4B285 for ; Mon, 27 Jun 2022 12:07:38 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id e61UHWAr-1Ql for ; Mon, 27 Jun 2022 12:07:37 -0400 (EDT) Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 7114849ECA for ; Mon, 27 Jun 2022 12:07:37 -0400 (EDT) Received: by mail-pl1-f172.google.com with SMTP id o18so8603233plg.2 for ; Mon, 27 Jun 2022 09:07:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=KXpJaULYCMOBvM0KZ+Y0QmYKcs5GsOT3UDoT12OxOmZTuofXiRwwGm/WgJTM1heXoI t1dv3k342OQnZ9iooXjd608cniWLl0qlDw2/EFrZO3JITiMUniSnoS9vRpsVYcQj8vN/ I7nko6H+yxfXlWmj6BpVmIQCvWqpF55RTmiG3dExwV8krl6JWA8dxuz7o3cuKUtlCKLL AUH1GrHaKcLi0AxNkq1Q0RlPIztx9SDq4ccjZXK7Aa2jkpBZXbRVUSJ+/fIBfJxIB9bo wqHrvEDbll+Qw87/iH2rzRcMOLCQ34VpKyfcZXoB0fUgM3GYU80A2xB80LHN6E80KQa1 5riQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=1fGwCmLerVUTAsWPuohmiOfoqzxJkzB2N3eYIcvEo30XbY7pk/7e86hVMy1UIu7yL2 Z1UiPhIHtez9zTdR22IbhWFW8Evgy6oQzlskbE5fFnYNyTk6V+/MuVjPYqqX4ItcDApX ILY8fYb4FupO0OVcAif/LjLTc8n6xNr23NZXPsfqg3GbYvLDE2ROQRZsV7sy61IR0fs3 KpS/ziZCV2a0XUKI0meRUg4B7SlyY6gwCsPHI7sbelv2ppwbJyYybHE/P+qkIAaaxQfY RW/M/vBk35hk5R2mC8wj7K9Lg7zWK1Io557ELQU4RJfmR3Y1WtHf14jZHSHh4xK/9YGy AzUA== X-Gm-Message-State: AJIora+L1QikG5UDtOLMSo8EpKW7b+qIVSEFP1UB/OOe/XO9aNXKNWOd vtkiWmRXcl9Cq3AVMLuxUrxSxQ== X-Google-Smtp-Source: AGRyM1uyfo5AfaNgmfF7G/qEE7dWnvzScXgctBWfKk3cum7fj6D7nx+TeglAS/qAbSPCsy6MAsmoPA== X-Received: by 2002:a17:902:9f97:b0:16a:9b9:fb63 with SMTP id g23-20020a1709029f9700b0016a09b9fb63mr15547216plq.7.1656346056250; Mon, 27 Jun 2022 09:07:36 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id g17-20020aa78191000000b005254bd90f22sm7528584pfi.150.2022.06.27.09.07.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 09:07:35 -0700 (PDT) Date: Mon, 27 Jun 2022 16:07:32 +0000 From: Sean Christopherson To: Yosry Ahmed Subject: Re: [PATCH v5 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Message-ID: References: <20220606222058.86688-1-yosryahmed@google.com> <20220606222058.86688-2-yosryahmed@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220606222058.86688-2-yosryahmed@google.com> Cc: Wanpeng Li , kvm@vger.kernel.org, Roman Gushchin , Michal Hocko , linux-mm@kvack.org, Zefan Li , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Joerg Roedel , Shakeel Butt , cgroups@vger.kernel.org, Andrew Morton , linux-arm-kernel@lists.infradead.org, Jim Mattson , linux-kernel@vger.kernel.org, Johannes Weiner , Tejun Heo , Paolo Bonzini , Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Mon, Jun 06, 2022, Yosry Ahmed wrote: > Add NR_SECONDARY_PAGETABLE stat to count secondary page table uses, e.g. > KVM mmu. This provides more insights on the kernel memory used > by a workload. Please provide more justification for NR_SECONDARY_PAGETABLE in the changelog. Specially, answer the questions that were asked in the previous version: 1. Why not piggyback NR_PAGETABLE? 2. Why a "generic" NR_SECONDARY_PAGETABLE instead of NR_VIRT_PAGETABLE? It doesn't have to be super long, but provide enough info so that reviewers and future readers don't need to go spelunking to understand the motivation for the new counter type. And it's probably worth an explicit Link to Marc's question that prompted the long discussion in the previous version, that way if someone does want the gory details they have a link readily available. Link: https://lore.kernel.org/all/87ilqoi77b.wl-maz@kernel.org _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EE50DC43334 for ; Mon, 27 Jun 2022 16:08:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gTAVh1HM/z5oy1fBOOvMTxxC873SVhZEQM3riXfSUh4=; b=iZh0OHGVb7Us/C 6E2eE+cUHZ1qjQcmWSzUo0DHkj7b8nG8VWe21jWFTxw9Ntygeq37r+qUhgT7BUzjOM1YlOTSp5lIv LUJ8SLsaq8ww5CpaX8Wc2TojC6uujpAjANfT18kD47JV35KTxv6im1iMlVitJF55/l/QDt0jpqtTo sVZ1If3E6akuukiPOargscFlJOguW/dQOVM6Dc+RFZs7ProOt7hqxSa/BqwJrLNOq2edA92yjzpGy qvgxSUsum9kmcmx1BDGwGMN+KaBnAEQpJTboQ+ucbU/fFhrsdxACDSXgjd6NEw+lGP6nb8ndg1ULe 4BaSsqpJODA/OsCzrg+A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o5rH2-001knH-Q0; Mon, 27 Jun 2022 16:07:40 +0000 Received: from mail-pj1-x1031.google.com ([2607:f8b0:4864:20::1031]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o5rGz-001kmD-Hj for linux-arm-kernel@lists.infradead.org; Mon, 27 Jun 2022 16:07:38 +0000 Received: by mail-pj1-x1031.google.com with SMTP id x1-20020a17090abc8100b001ec7f8a51f5so12979140pjr.0 for ; Mon, 27 Jun 2022 09:07:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=KXpJaULYCMOBvM0KZ+Y0QmYKcs5GsOT3UDoT12OxOmZTuofXiRwwGm/WgJTM1heXoI t1dv3k342OQnZ9iooXjd608cniWLl0qlDw2/EFrZO3JITiMUniSnoS9vRpsVYcQj8vN/ I7nko6H+yxfXlWmj6BpVmIQCvWqpF55RTmiG3dExwV8krl6JWA8dxuz7o3cuKUtlCKLL AUH1GrHaKcLi0AxNkq1Q0RlPIztx9SDq4ccjZXK7Aa2jkpBZXbRVUSJ+/fIBfJxIB9bo wqHrvEDbll+Qw87/iH2rzRcMOLCQ34VpKyfcZXoB0fUgM3GYU80A2xB80LHN6E80KQa1 5riQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=pLE+WPTw5zf4HZXAiH+3tm8iSLITVJqJTw/prcyIFkKEzm+MozCdLg4ncwitf+HHvo LkXGLKhz39icfJ9QX7kQSkiFV0ze0FPceezlzz/r7mrUlova88RmS4QMg+G8mMseomnM N/HTFvJe+akEfqUyDK0vmvYIRT0yw0NUQBxJ1X5VDSfzSyig0hwkKIQGpPhrKVzpZTKa GNXxtvYTDIuGuBW2kUChw+6QH1OwjDikVkjYlT3I24VhON9vetgykwGIG7CSY9wuaovv Hrv3Zg+7TFuQhiH24YjndIgZK2YnZb/Detct3NbEx0LKKu/aQ7L6iBkn0ddeYjVlf4tb 65Ag== X-Gm-Message-State: AJIora9BB03IcrNm+e8NpgNNAKXx8VAD1iicHJxRLFX5OH0hclOjhDk8 8HTK0CCsW25VLpn7iRWKZoNu4w== X-Google-Smtp-Source: AGRyM1uyfo5AfaNgmfF7G/qEE7dWnvzScXgctBWfKk3cum7fj6D7nx+TeglAS/qAbSPCsy6MAsmoPA== X-Received: by 2002:a17:902:9f97:b0:16a:9b9:fb63 with SMTP id g23-20020a1709029f9700b0016a09b9fb63mr15547216plq.7.1656346056250; Mon, 27 Jun 2022 09:07:36 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id g17-20020aa78191000000b005254bd90f22sm7528584pfi.150.2022.06.27.09.07.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 09:07:35 -0700 (PDT) Date: Mon, 27 Jun 2022 16:07:32 +0000 From: Sean Christopherson To: Yosry Ahmed Cc: Tejun Heo , Johannes Weiner , Zefan Li , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Andrew Morton , Michal Hocko , Roman Gushchin , Shakeel Butt , Oliver Upton , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v5 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Message-ID: References: <20220606222058.86688-1-yosryahmed@google.com> <20220606222058.86688-2-yosryahmed@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220606222058.86688-2-yosryahmed@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220627_090737_625788_89110C92 X-CRM114-Status: UNSURE ( 9.85 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 06, 2022, Yosry Ahmed wrote: > Add NR_SECONDARY_PAGETABLE stat to count secondary page table uses, e.g. > KVM mmu. This provides more insights on the kernel memory used > by a workload. Please provide more justification for NR_SECONDARY_PAGETABLE in the changelog. Specially, answer the questions that were asked in the previous version: 1. Why not piggyback NR_PAGETABLE? 2. Why a "generic" NR_SECONDARY_PAGETABLE instead of NR_VIRT_PAGETABLE? It doesn't have to be super long, but provide enough info so that reviewers and future readers don't need to go spelunking to understand the motivation for the new counter type. And it's probably worth an explicit Link to Marc's question that prompted the long discussion in the previous version, that way if someone does want the gory details they have a link readily available. Link: https://lore.kernel.org/all/87ilqoi77b.wl-maz@kernel.org _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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 ACB25C433EF for ; Mon, 27 Jun 2022 16:08:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238924AbiF0QIA (ORCPT ); Mon, 27 Jun 2022 12:08:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239039AbiF0QHk (ORCPT ); Mon, 27 Jun 2022 12:07:40 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00D9215705 for ; Mon, 27 Jun 2022 09:07:37 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id x1-20020a17090abc8100b001ec7f8a51f5so12979139pjr.0 for ; Mon, 27 Jun 2022 09:07:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=KXpJaULYCMOBvM0KZ+Y0QmYKcs5GsOT3UDoT12OxOmZTuofXiRwwGm/WgJTM1heXoI t1dv3k342OQnZ9iooXjd608cniWLl0qlDw2/EFrZO3JITiMUniSnoS9vRpsVYcQj8vN/ I7nko6H+yxfXlWmj6BpVmIQCvWqpF55RTmiG3dExwV8krl6JWA8dxuz7o3cuKUtlCKLL AUH1GrHaKcLi0AxNkq1Q0RlPIztx9SDq4ccjZXK7Aa2jkpBZXbRVUSJ+/fIBfJxIB9bo wqHrvEDbll+Qw87/iH2rzRcMOLCQ34VpKyfcZXoB0fUgM3GYU80A2xB80LHN6E80KQa1 5riQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=l0pibN8bjG0PnvfGdr94sagjrAjKQlwTKx4ke7hg5TE=; b=sBsyV7UHUocP0J1qBvMb+Og+Sko4MFj27gj0ksKQYJWcZpQKbxr9cHY4IWG8m6YrKu 3LkvWtLExUaRswVbSdhOBE6R5WKrnsAGuZtYJ5K0oR6UUK21HLcqxtfAnO2SyZVUiPqH Iv9gyAHEOIx68Wr9La87ebGa9sU94u2UnmKzQpr7K3aN/rUnaO5BZCm/c0DQmC6APuT3 l6ViHj1xI7CmyO5+ftPbXvJoNYAwQwRsDHAYYVbzQmq/0u3TAIa4pF8KGBnx3jP+qMlP ZqWSoizh/zw2TUpc90wr1YYK4xFpiitk4/AUd5EMVvYTRFNz6EQIC8PUtQ525UrVNuhv V/eA== X-Gm-Message-State: AJIora+c4z9wPgHvOKJN6aOkfK/UI7W0Ug53u8TJGc30qK/zbZPFbEQO xwrZoZiH5r6Iv8/3qHXHXS7q9g== X-Google-Smtp-Source: AGRyM1uyfo5AfaNgmfF7G/qEE7dWnvzScXgctBWfKk3cum7fj6D7nx+TeglAS/qAbSPCsy6MAsmoPA== X-Received: by 2002:a17:902:9f97:b0:16a:9b9:fb63 with SMTP id g23-20020a1709029f9700b0016a09b9fb63mr15547216plq.7.1656346056250; Mon, 27 Jun 2022 09:07:36 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id g17-20020aa78191000000b005254bd90f22sm7528584pfi.150.2022.06.27.09.07.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 09:07:35 -0700 (PDT) Date: Mon, 27 Jun 2022 16:07:32 +0000 From: Sean Christopherson To: Yosry Ahmed Cc: Tejun Heo , Johannes Weiner , Zefan Li , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Andrew Morton , Michal Hocko , Roman Gushchin , Shakeel Butt , Oliver Upton , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v5 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Message-ID: References: <20220606222058.86688-1-yosryahmed@google.com> <20220606222058.86688-2-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220606222058.86688-2-yosryahmed@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Jun 06, 2022, Yosry Ahmed wrote: > Add NR_SECONDARY_PAGETABLE stat to count secondary page table uses, e.g. > KVM mmu. This provides more insights on the kernel memory used > by a workload. Please provide more justification for NR_SECONDARY_PAGETABLE in the changelog. Specially, answer the questions that were asked in the previous version: 1. Why not piggyback NR_PAGETABLE? 2. Why a "generic" NR_SECONDARY_PAGETABLE instead of NR_VIRT_PAGETABLE? It doesn't have to be super long, but provide enough info so that reviewers and future readers don't need to go spelunking to understand the motivation for the new counter type. And it's probably worth an explicit Link to Marc's question that prompted the long discussion in the previous version, that way if someone does want the gory details they have a link readily available. Link: https://lore.kernel.org/all/87ilqoi77b.wl-maz@kernel.org