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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2434DC433EF for ; Mon, 18 Oct 2021 15:11:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08C53610A1 for ; Mon, 18 Oct 2021 15:11:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233534AbhJRPNx (ORCPT ); Mon, 18 Oct 2021 11:13:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58387 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233594AbhJRPNv (ORCPT ); Mon, 18 Oct 2021 11:13:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634569900; 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=5bcXVhCSgmfoL1hBJhvkBctTXiNXtHjcm3bxLuf2Zkw=; b=IoJeF1sPTxk4D00pcIpUm/AqYINooCLu1RkGPdfSyQ4RLEIQYEGxSWuO6jc5Xx+OkzGhUb VQwrLZKyeaXlf2iFkMSy4XGRwUq2aF2VlV5D9pmPqLrQSyB387GPqADOCyPU3yY99O70WF 9VP0ZRM41p7erVT8sIV9tEzQRVuswAc= 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-213-0wGNrIwTPwW2v9khfA_aRg-1; Mon, 18 Oct 2021 11:11:35 -0400 X-MC-Unique: 0wGNrIwTPwW2v9khfA_aRg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 81222809CDB; Mon, 18 Oct 2021 15:11:34 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.33.34]) by smtp.corp.redhat.com (Postfix) with ESMTP id B22ED60C82; Mon, 18 Oct 2021 15:11:11 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 47E8E2256EE; Mon, 18 Oct 2021 11:11:11 -0400 (EDT) Date: Mon, 18 Oct 2021 11:11:11 -0400 From: Vivek Goyal To: Jeffle Xu Cc: stefanha@redhat.com, miklos@szeredi.hub, linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com, bo.liu@linux.alibaba.com, joseph.qi@linux.alibaba.com Subject: Re: [PATCH v6 5/7] fuse: enable per-file DAX Message-ID: References: <20211011030052.98923-1-jefflexu@linux.alibaba.com> <20211011030052.98923-6-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211011030052.98923-6-jefflexu@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Oct 11, 2021 at 11:00:50AM +0800, Jeffle Xu wrote: > DAX may be limited in some specific situation. When the number of usable > DAX windows is under watermark, the recalim routine will be triggered to > reclaim some DAX windows. It may have a negative impact on the > performance, since some processes may need to wait for DAX windows to be > recalimed and reused then. To mitigate the performance degradation, the > overall DAX window need to be expanded larger. > > However, simply expanding the DAX window may not be a good deal in some > scenario. To maintain one DAX window chunk (i.e., 2MB in size), 32KB > (512 * 64 bytes) memory footprint will be consumed for page descriptors > inside guest, which is greater than the memory footprint if it uses > guest page cache when DAX disabled. Thus it'd better disable DAX for > those files smaller than 32KB, to reduce the demand for DAX window and > thus avoid the unworthy memory overhead. > > Per-file DAX feature is introduced to address this issue, by offering a > finer grained control for dax to users, trying to achieve a balance > between performance and memory overhead. > > The FUSE_ATTR_DAX flag in FUSE_LOOKUP reply is used to indicate whether > DAX should be enabled or not for corresponding file. Currently the state > whether DAX is enabled or not for the file is initialized only when > inode is instantiated. > > Signed-off-by: Jeffle Xu > --- > fs/fuse/dax.c | 8 ++++---- > fs/fuse/file.c | 4 ++-- > fs/fuse/fuse_i.h | 4 ++-- > fs/fuse/inode.c | 2 +- > 4 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c > index 4c6c64efc950..15bde36829b8 100644 > --- a/fs/fuse/dax.c > +++ b/fs/fuse/dax.c > @@ -1335,7 +1335,7 @@ static const struct address_space_operations fuse_dax_file_aops = { > .invalidatepage = noop_invalidatepage, > }; > > -static bool fuse_should_enable_dax(struct inode *inode) > +static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags) > { > struct fuse_conn *fc = get_fuse_conn(inode); > unsigned int dax_mode = fc->dax_mode; > @@ -1352,12 +1352,12 @@ static bool fuse_should_enable_dax(struct inode *inode) > return true; > > /* dax_mode == FUSE_DAX_INODE */ > - return true; > + return flags & FUSE_ATTR_DAX; > } > > -void fuse_dax_inode_init(struct inode *inode) > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags) ^^^^ These are attr->flags. May be call this variable attr_flags so that it is more clear. Vivek > { > - if (!fuse_should_enable_dax(inode)) > + if (!fuse_should_enable_dax(inode, flags)) > return; > > inode->i_flags |= S_DAX; > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 11404f8c21c7..40c667a48cf6 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3163,7 +3163,7 @@ static const struct address_space_operations fuse_file_aops = { > .write_end = fuse_write_end, > }; > > -void fuse_init_file_inode(struct inode *inode) > +void fuse_init_file_inode(struct inode *inode, unsigned int flags) > { > struct fuse_inode *fi = get_fuse_inode(inode); > > @@ -3177,5 +3177,5 @@ void fuse_init_file_inode(struct inode *inode) > fi->writepages = RB_ROOT; > > if (IS_ENABLED(CONFIG_FUSE_DAX)) > - fuse_dax_inode_init(inode); > + fuse_dax_inode_init(inode, flags); > } > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index 5abf9749923f..0270a41c31d7 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -1016,7 +1016,7 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc, > /** > * Initialize file operations on a regular file > */ > -void fuse_init_file_inode(struct inode *inode); > +void fuse_init_file_inode(struct inode *inode, unsigned int flags); > > /** > * Initialize inode operations on regular files and special files > @@ -1268,7 +1268,7 @@ int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode mode, > struct dax_device *dax_dev); > void fuse_dax_conn_free(struct fuse_conn *fc); > bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi); > -void fuse_dax_inode_init(struct inode *inode); > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags); > void fuse_dax_inode_cleanup(struct inode *inode); > bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment); > void fuse_dax_cancel_work(struct fuse_conn *fc); > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > index f4ad99e2415b..73f19cd6e702 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -280,7 +280,7 @@ static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr) > inode->i_ctime.tv_nsec = attr->ctimensec; > if (S_ISREG(inode->i_mode)) { > fuse_init_common(inode); > - fuse_init_file_inode(inode); > + fuse_init_file_inode(inode, attr->flags); > } else if (S_ISDIR(inode->i_mode)) > fuse_init_dir(inode); > else if (S_ISLNK(inode->i_mode)) > -- > 2.27.0 >