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=-5.9 required=3.0 tests=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=ham 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 0E513C282DD for ; Thu, 9 Jan 2020 16:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D599E20661 for ; Thu, 9 Jan 2020 16:17:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="b412CnJI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387595AbgAIQRv (ORCPT ); Thu, 9 Jan 2020 11:17:51 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:47963 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730483AbgAIQRt (ORCPT ); Thu, 9 Jan 2020 11:17:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578586669; 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: in-reply-to:in-reply-to:references:references; bh=utdlm/aKlY7xAQfEyR3w7Eafs4aRDid1gJnviBYktXw=; b=b412CnJIyZx0RcnAjmPw1hVXuHrWKydt40cxRNZhmiEfn9bDrBoR/LFo4SdbNXv/C3UF6b cq1nsF6Uhi8ewafwQz9Kb3bL4kMQ3d7m+CJUDzTH0QSN3ogelNOo38m9Ayipl9X6m3M9w/ LlhxPuMRKNaQH6xM+p1hmQ/xWZWABcE= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-49-8gmgBvSWP3-oSv7hUfqH4A-1; Thu, 09 Jan 2020 11:17:45 -0500 X-MC-Unique: 8gmgBvSWP3-oSv7hUfqH4A-1 Received: by mail-qk1-f199.google.com with SMTP id x127so4477017qkb.0 for ; Thu, 09 Jan 2020 08:17:45 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=utdlm/aKlY7xAQfEyR3w7Eafs4aRDid1gJnviBYktXw=; b=FOeoHBxZiQFYWH3WnSfR1vO/j8ft9vBqxAXN9ACKZQdan78wabhPPD3R1NQg2Sneev vVDW6QmD8RxzvCo6ezvBN9Ad2zffyVNSXG8bhuXSaUjxNsBCfWdYMCgsouvVt0qU/250 l3X49dzcCoR8nGyWAGNeNRXQLsf2fwT7gylGYQgY8zEip595ht30j9nOyPwvRAw4wrwT 0IE4UfPXsuFZiw0yDHWqj7RMp+C3bupB/KpU/Y+/qUrNSrm2E8tXIuFP08klNF9VVRia Lsw2PzTdpAhLyWUqawBVg6GaYnvKnOXOeb4XYylY7KNH2HT4PAy6IsX5OD0/d0eXPGem 7uWQ== X-Gm-Message-State: APjAAAXBFiVKI1hLl7zwoYmaci+px9s2ybYNstZTlFQAoXFCEmrV9MF0 w9/8SVpQd5d61XVH/tEZHTDaZa7bCWrdKJSveqO1Je7vnnhs+vZlai0S2laUFlCPr/oVL1T8sYe Ut+Ftad7BPRpmMoN/e/xPF6zq X-Received: by 2002:ac8:544f:: with SMTP id d15mr8718695qtq.53.1578586665331; Thu, 09 Jan 2020 08:17:45 -0800 (PST) X-Google-Smtp-Source: APXvYqxOO77lSOX4HB1VsYJg95F5t9IBQf4gOicmO1+VK8TA5tARhYVtiz9nWGF7JPyZNSOqo/KKIw== X-Received: by 2002:ac8:544f:: with SMTP id d15mr8718671qtq.53.1578586665141; Thu, 09 Jan 2020 08:17:45 -0800 (PST) Received: from xz-x1 ([104.156.64.74]) by smtp.gmail.com with ESMTPSA id m8sm3602484qtk.60.2020.01.09.08.17.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2020 08:17:43 -0800 (PST) Date: Thu, 9 Jan 2020 11:17:42 -0500 From: Peter Xu To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Christophe de Dinechin , Paolo Bonzini , Sean Christopherson , Yan Zhao , Alex Williamson , Jason Wang , Kevin Kevin , Vitaly Kuznetsov , "Dr . David Alan Gilbert" Subject: Re: [PATCH v3 00/21] KVM: Dirty ring interface Message-ID: <20200109161742.GC15671@xz-x1> References: <20200109145729.32898-1-peterx@redhat.com> <20200109105443-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200109105443-mutt-send-email-mst@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 09, 2020 at 10:59:50AM -0500, Michael S. Tsirkin wrote: > On Thu, Jan 09, 2020 at 09:57:08AM -0500, Peter Xu wrote: > > Branch is here: https://github.com/xzpeter/linux/tree/kvm-dirty-ring > > (based on kvm/queue) > > > > Please refer to either the previous cover letters, or documentation > > update in patch 12 for the big picture. > > I would rather you pasted it here. There's no way to respond otherwise. Sure, will do in the next post. > > For something that's presumably an optimization, isn't there > some kind of testing that can be done to show the benefits? > What kind of gain was observed? Since the interface seems to settle soon, maybe it's time to work on the QEMU part so I can give some number. It would be interesting to know the curves between dirty logging and dirty ring even for some small vms that have some workloads inside. > > I know it's mostly relevant for huge VMs, but OTOH these > probably use huge pages. Yes huge VMs could benefit more, especially if the dirty rate is not that high, I believe. Though, could you elaborate on why huge pages are special here? Thanks, -- Peter Xu