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=-6.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 364C1C4320A for ; Tue, 17 Aug 2021 12:49:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 155EC60EE4 for ; Tue, 17 Aug 2021 12:49:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236658AbhHQMuH (ORCPT ); Tue, 17 Aug 2021 08:50:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60723 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbhHQMuD (ORCPT ); Tue, 17 Aug 2021 08:50:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629204570; 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=vcCKqyTQplJmhM6jbmzOZVZZmwW62f89g7PD6tqdQoc=; b=DDbQB0PPCqHQDgPzRSQx3tZAKhadpNe9yotWiSh9/h/qgRpZtVJAx2lfmJ5gKnGw0UUXf7 EE00gE5EtYzU7HwpCre8UuQ7iTXyUmq0xd8Dk+lAe0ycKR+cQK5T9vQLa7CgTgXNAesmUn SrRNrG+/33Ge4X+7GEi0956QJTHe7ew= 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-359-lnzeZJRfOcihOzliFUjK4w-1; Tue, 17 Aug 2021 08:49:28 -0400 X-MC-Unique: lnzeZJRfOcihOzliFUjK4w-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5A49B1026200; Tue, 17 Aug 2021 12:49:27 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.10.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4BB4769280; Tue, 17 Aug 2021 12:49:23 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 7D68F2281A8; Tue, 17 Aug 2021 08:40:38 -0400 (EDT) Date: Tue, 17 Aug 2021 08:40:38 -0400 From: Vivek Goyal To: "Dr. David Alan Gilbert" Cc: Miklos Szeredi , Jeffle Xu , virtualization@lists.linux-foundation.org, virtio-fs-list , Joseph Qi , linux-fsdevel@vger.kernel.org Subject: Re: [Virtio-fs] [PATCH v4 0/8] fuse,virtiofs: support per-file DAX Message-ID: References: <20210817022220.17574-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Aug 17, 2021 at 10:32:14AM +0100, Dr. David Alan Gilbert wrote: > * Miklos Szeredi (miklos@szeredi.hu) wrote: > > On Tue, 17 Aug 2021 at 04:22, Jeffle Xu wrote: > > > > > > This patchset adds support of per-file DAX for virtiofs, which is > > > inspired by Ira Weiny's work on ext4[1] and xfs[2]. > > > > Can you please explain the background of this change in detail? > > > > Why would an admin want to enable DAX for a particular virtiofs file > > and not for others? > > Where we're contending on virtiofs dax cache size it makes a lot of > sense; it's quite expensive for us to map something into the cache > (especially if we push something else out), so selectively DAXing files > that are expected to be hot could help reduce cache churn. In that case probaly we should just make DAX window larger. I assume that selecting which files to turn DAX on, will itself will not be a trivial. Not sure what heuristics are being deployed to determine that. Will like to know more about it. Vivek