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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 349E5C4361B for ; Fri, 11 Dec 2020 19:38:23 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E5CB23D97 for ; Fri, 11 Dec 2020 19:38:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E5CB23D97 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34318 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1knoFB-0001yI-7t for qemu-devel@archiver.kernel.org; Fri, 11 Dec 2020 14:38:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:52560) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kno2s-0001qK-W7 for qemu-devel@nongnu.org; Fri, 11 Dec 2020 14:25:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:59495) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kno2l-0004XA-Nn for qemu-devel@nongnu.org; Fri, 11 Dec 2020 14:25:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607714727; 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=kI3DtFLJ4w3kifQLWYYVC5R11Drutd2LMD1HSRJJPIA=; b=UMhiGibwzTcBPOZG/eI25pMU23Kaox9thrlSPnQM7bOPXn/4XfNoMyhgtGRXh+yGtRWAdd PPxApfCxVjOP9+3KqkQJZpxcGkHBEPMfr5griTb7P6Z5clMAKP6Az7HQdUokwc4U7w0O7A zPQRwgTJva8VeXUfpxNBSxRA92Biqn0= 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-250-HlrsgmalNQmJT-bB3QKXuA-1; Fri, 11 Dec 2020 14:25:25 -0500 X-MC-Unique: HlrsgmalNQmJT-bB3QKXuA-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 9A39E10054FF; Fri, 11 Dec 2020 19:25:24 +0000 (UTC) Received: from horse.redhat.com (ovpn-115-237.rdu2.redhat.com [10.10.115.237]) by smtp.corp.redhat.com (Postfix) with ESMTP id 073A91992D; Fri, 11 Dec 2020 19:25:18 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 90666220BCF; Fri, 11 Dec 2020 14:25:17 -0500 (EST) Date: Fri, 11 Dec 2020 14:25:17 -0500 From: Vivek Goyal To: "Dr. David Alan Gilbert" Subject: Re: Some performance numbers for virtiofs, DAX and virtio-9p Message-ID: <20201211192517.GF3285@redhat.com> References: <20201210161126.GA125438@redhat.com> <20201211160603.GD3285@redhat.com> <20201211182956.GF3380@work-vm> MIME-Version: 1.0 In-Reply-To: <20201211182956.GF3380@work-vm> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vgoyal@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Miklos Szeredi , "Venegas Munoz, Jose Carlos" , Christian Schoenebeck , QEMU Developers , virtio-fs-list , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Dec 11, 2020 at 06:29:56PM +0000, Dr. David Alan Gilbert wrote: [..] > > > > > > Could we measure at what point does a large window size actually make > > > performance worse? > > > > Will do. Will run tests with varying window sizes (small to large) > > and see how does it impact performance for same workload with > > same guest memory. > > I wonder how realistic it is though; it makes some sense if you have a > scenario like a fairly small root filesystem - something tractable; but > if you have a large FS you're not realistically going to be able to set > the cache size to match it - that's why it's a cache! I think its more about active dataset size and not necessarily total FS size. FS might be big but if application is not accessing all of the in reasonabl small time window, then it does not matter. What worries me most is that cost of reclaim of a dax range seems too high (or keeps the process blocked for long enogh), that it kills the performance. I will need to revisit the reclaim path and see if I can optimize something. Vivek