From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Waiman Long <longman@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-ext4@vger.kernel.org, cluster-devel@redhat.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: RFC: hold i_rwsem until aio completes
Date: Mon, 3 Feb 2020 18:44:21 +0100 [thread overview]
Message-ID: <20200203174421.GB20001@lst.de> (raw)
In-Reply-To: <20200116140004.GE8446@quack2.suse.cz>
On Thu, Jan 16, 2020 at 03:00:04PM +0100, Jan Kara wrote:
> I'd like to note that using i_dio_count has also one advantage you didn't
> mention. For AIO case, if you need to hold i_rwsem in exclusive mode,
> holding the i_rwsem just for submission part is a significant performance
> advantage (shorter lock hold times allow for higher IO parallelism). I
> guess this could be mitigated by downgrading the lock to shared mode
> once the IO is submitted. But there will be still some degradation visible
> for the cases of mixed exclusive and shared acquisitions because shared
> holders will be blocking exclusive ones for longer time.
>
> This may be especially painful for filesystems that don't implement DIO
> overwrites with i_rwsem in shared mode...
True. Fortunately there are patches for ext4 out to move over to that
scheme. gfs2 will need a little more attention, but that also for other
reasons.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] RFC: hold i_rwsem until aio completes
Date: Mon, 3 Feb 2020 18:44:21 +0100 [thread overview]
Message-ID: <20200203174421.GB20001@lst.de> (raw)
In-Reply-To: <20200116140004.GE8446@quack2.suse.cz>
On Thu, Jan 16, 2020 at 03:00:04PM +0100, Jan Kara wrote:
> I'd like to note that using i_dio_count has also one advantage you didn't
> mention. For AIO case, if you need to hold i_rwsem in exclusive mode,
> holding the i_rwsem just for submission part is a significant performance
> advantage (shorter lock hold times allow for higher IO parallelism). I
> guess this could be mitigated by downgrading the lock to shared mode
> once the IO is submitted. But there will be still some degradation visible
> for the cases of mixed exclusive and shared acquisitions because shared
> holders will be blocking exclusive ones for longer time.
>
> This may be especially painful for filesystems that don't implement DIO
> overwrites with i_rwsem in shared mode...
True. Fortunately there are patches for ext4 out to move over to that
scheme. gfs2 will need a little more attention, but that also for other
reasons.
next prev parent reply other threads:[~2020-02-03 17:44 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 16:12 RFC: hold i_rwsem until aio completes Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 01/12] mm: fix a comment in sys_swapon Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-02-10 23:29 ` Andrew Morton
2020-02-10 23:29 ` [Cluster-devel] " Andrew Morton
2020-02-12 7:37 ` Christoph Hellwig
2020-02-12 7:37 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 02/12] locking/rwsem: Exit early when held by an anonymous owner Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 18:17 ` Waiman Long
2020-01-14 18:17 ` [Cluster-devel] " Waiman Long
2020-01-14 18:25 ` Christoph Hellwig
2020-01-14 18:25 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 18:33 ` Waiman Long
2020-01-14 18:33 ` [Cluster-devel] " Waiman Long
2020-01-14 18:55 ` Waiman Long
2020-01-14 18:55 ` [Cluster-devel] " Waiman Long
2020-01-14 16:12 ` [PATCH 03/12] xfs: fix IOCB_NOWAIT handling in xfs_file_dio_aio_read Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 04/12] gfs2: move setting current->backing_dev_info Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 05/12] gfs2: fix O_SYNC write handling Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-27 9:03 ` Christoph Hellwig
2020-01-28 16:57 ` Bob Peterson
2020-02-06 15:31 ` Andreas Gruenbacher
2020-02-06 15:31 ` Andreas Gruenbacher
2020-02-06 15:31 ` Andreas Gruenbacher
2020-01-14 16:12 ` [PATCH 06/12] iomap: pass a flags value to iomap_dio_rw Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 07/12] iomap: allow holding i_rwsem until aio completion Christoph Hellwig
2020-01-14 16:12 ` [PATCH 08/12] ext4: hold i_rwsem until AIO completes Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 21:50 ` Theodore Y. Ts'o
2020-01-14 21:50 ` [Cluster-devel] " Theodore Y. Ts'o
2020-01-15 6:48 ` Christoph Hellwig
2020-01-15 6:48 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 09/12] gfs2: " Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 10/12] xfs: " Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 11/12] xfs: don't set IOMAP_DIO_SYNCHRONOUS for unaligned I/O Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 16:12 ` [PATCH 12/12] iomap: remove the inode_dio_begin/end calls Christoph Hellwig
2020-01-14 16:12 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 18:47 ` RFC: hold i_rwsem until aio completes Matthew Wilcox
2020-01-14 18:47 ` [Cluster-devel] " Matthew Wilcox
2020-01-15 6:54 ` Christoph Hellwig
2020-01-15 6:54 ` [Cluster-devel] " Christoph Hellwig
2020-01-14 19:27 ` Jason Gunthorpe
2020-01-14 19:27 ` [Cluster-devel] " Jason Gunthorpe
2020-01-15 6:56 ` Christoph Hellwig
2020-01-15 6:56 ` [Cluster-devel] " Christoph Hellwig
2020-01-15 13:24 ` Jason Gunthorpe
2020-01-15 13:24 ` [Cluster-devel] " Jason Gunthorpe
2020-01-15 14:33 ` Peter Zijlstra
2020-01-15 14:33 ` [Cluster-devel] " Peter Zijlstra
2020-01-15 14:49 ` Jason Gunthorpe
2020-01-15 14:49 ` [Cluster-devel] " Jason Gunthorpe
2020-01-15 19:03 ` Waiman Long
2020-01-15 19:03 ` [Cluster-devel] " Waiman Long
2020-01-15 19:07 ` Christoph Hellwig
2020-01-15 19:07 ` [Cluster-devel] " Christoph Hellwig
2020-01-18 22:40 ` Matthew Wilcox
2020-01-18 22:40 ` [Cluster-devel] " Matthew Wilcox
2020-01-15 15:36 ` Christoph Hellwig
2020-01-15 15:36 ` [Cluster-devel] " Christoph Hellwig
2020-01-15 16:26 ` Jason Gunthorpe
2020-01-15 16:26 ` [Cluster-devel] " Jason Gunthorpe
2020-01-16 14:00 ` Jan Kara
2020-01-16 14:00 ` [Cluster-devel] " Jan Kara
2020-02-03 17:44 ` Christoph Hellwig [this message]
2020-02-03 17:44 ` Christoph Hellwig
2020-01-18 9:28 ` Dave Chinner
2020-01-18 9:28 ` [Cluster-devel] " Dave Chinner
2020-02-03 17:46 ` Christoph Hellwig
2020-02-03 17:46 ` [Cluster-devel] " Christoph Hellwig
2020-02-03 23:02 ` Dave Chinner
2020-02-03 23:02 ` [Cluster-devel] " Dave Chinner
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