From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 13 Dec 2021 13:10:00 -0500 From: Vivek Goyal Message-ID: References: <20211125070530.79602-1-jefflexu@linux.alibaba.com> <20211125070530.79602-5-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211125070530.79602-5-jefflexu@linux.alibaba.com> Subject: Re: [Virtio-fs] [PATCH v8 4/7] fuse: enable per inode DAX List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jeffle Xu Cc: virtio-fs@redhat.com, linux-fsdevel@vger.kernel.org, joseph.qi@linux.alibaba.com, miklos@szeredi.hu On Thu, Nov 25, 2021 at 03:05:27PM +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 inode 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 Reviwed-by: Vivek Goyal Vivek > --- > fs/fuse/dax.c | 12 ++++++++---- > fs/fuse/file.c | 4 ++-- > fs/fuse/fuse_i.h | 4 ++-- > fs/fuse/inode.c | 2 +- > 4 files changed, 13 insertions(+), 9 deletions(-) > > diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c > index b9a031a82934..1550c3624414 100644 > --- a/fs/fuse/dax.c > +++ b/fs/fuse/dax.c > @@ -1332,7 +1332,7 @@ 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); > enum fuse_dax_mode dax_mode = fc->dax_mode; > @@ -1347,12 +1347,16 @@ static bool fuse_should_enable_dax(struct inode *inode) > if (!fc->dax) > return false; > > - return true; > + if (dax_mode == FUSE_DAX_ALWAYS) > + return true; > + > + /* dax_mode is FUSE_DAX_INODE* */ > + return flags & FUSE_ATTR_DAX; > } > > -void fuse_dax_inode_init(struct inode *inode) > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags) > { > - 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 9d6c5f6361f7..90067584e103 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3169,7 +3169,7 @@ 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); > > @@ -3183,5 +3183,5 @@ 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 19ded93cfc49..f03ea7cb74b0 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -1022,7 +1022,7 @@ 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 > @@ -1288,7 +1288,7 @@ 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 4a41e6a73f3f..0669e41a9645 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -313,7 +313,7 @@ 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 > 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 8D289C433EF for ; Mon, 13 Dec 2021 18:10:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238876AbhLMSKY (ORCPT ); Mon, 13 Dec 2021 13:10:24 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:25413 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236073AbhLMSKX (ORCPT ); Mon, 13 Dec 2021 13:10:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639419023; 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=bkTXlAxjpUMN9ROvU9HyidRRvaYLz97A1f1Rn9U9Zmo=; b=O4WhFbortgoQqdGxYcLpa65sgbtWAkxWE6UBY/X97d65XMq1siPfnOLtv9QjApX2iDJbSb vaL6KZ19eve0bJSRARbX3ff+8UFCo1dmdTW0O+dqK/izY04yizgVvjyFCUlGsXVjLO1wUC O78/1o0t56g49vRAg2IN02rklFSRzjs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-462-PCW2oPcLMU23WahrYaNDoA-1; Mon, 13 Dec 2021 13:10:19 -0500 X-MC-Unique: PCW2oPcLMU23WahrYaNDoA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B9E8D192FDA1; Mon, 13 Dec 2021 18:10:18 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.17.75]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9D9315E272; Mon, 13 Dec 2021 18:10:00 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 35C0A2233DF; Mon, 13 Dec 2021 13:10:00 -0500 (EST) Date: Mon, 13 Dec 2021 13:10:00 -0500 From: Vivek Goyal To: Jeffle Xu Cc: stefanha@redhat.com, miklos@szeredi.hu, virtio-fs@redhat.com, linux-fsdevel@vger.kernel.org, joseph.qi@linux.alibaba.com Subject: Re: [PATCH v8 4/7] fuse: enable per inode DAX Message-ID: References: <20211125070530.79602-1-jefflexu@linux.alibaba.com> <20211125070530.79602-5-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211125070530.79602-5-jefflexu@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Nov 25, 2021 at 03:05:27PM +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 inode 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 Reviwed-by: Vivek Goyal Vivek > --- > fs/fuse/dax.c | 12 ++++++++---- > fs/fuse/file.c | 4 ++-- > fs/fuse/fuse_i.h | 4 ++-- > fs/fuse/inode.c | 2 +- > 4 files changed, 13 insertions(+), 9 deletions(-) > > diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c > index b9a031a82934..1550c3624414 100644 > --- a/fs/fuse/dax.c > +++ b/fs/fuse/dax.c > @@ -1332,7 +1332,7 @@ 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); > enum fuse_dax_mode dax_mode = fc->dax_mode; > @@ -1347,12 +1347,16 @@ static bool fuse_should_enable_dax(struct inode *inode) > if (!fc->dax) > return false; > > - return true; > + if (dax_mode == FUSE_DAX_ALWAYS) > + return true; > + > + /* dax_mode is FUSE_DAX_INODE* */ > + return flags & FUSE_ATTR_DAX; > } > > -void fuse_dax_inode_init(struct inode *inode) > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags) > { > - 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 9d6c5f6361f7..90067584e103 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3169,7 +3169,7 @@ 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); > > @@ -3183,5 +3183,5 @@ 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 19ded93cfc49..f03ea7cb74b0 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -1022,7 +1022,7 @@ 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 > @@ -1288,7 +1288,7 @@ 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 4a41e6a73f3f..0669e41a9645 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -313,7 +313,7 @@ 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 >