From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Waiman Long <waiman.long@hpe.com>,
"Theodore Ts'o" <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Matthew Wilcox <willy@linux.intel.com>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>,
Toshimitsu Kani <toshi.kani@hpe.com>
Subject: Re: [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM
Date: Thu, 5 May 2016 07:19:32 -0700 [thread overview]
Message-ID: <20160505141932.GA29221@infradead.org> (raw)
In-Reply-To: <20160505015730.GC26977@dastard>
On Thu, May 05, 2016 at 11:57:30AM +1000, Dave Chinner wrote:
> We did this intentionally. DAX IO needs to have the same parallel
> write semantics of direct IO, because otherwise a single writer
> prevents any IO concurrency and that's a bigger problem for DAX that
> traditional storage due to the access speed and bandwidth available.
But this is secondard - even buffered I/O would benefit from not
having the global lock. The difference is that Posix requires exclusive
writers, and we can't just break those semantics because we're sitting
on whizz bang fancy backend storage.
prev parent reply other threads:[~2016-05-05 14:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-29 16:27 [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-04-29 16:27 ` [PATCH v5 1/2] dax: Don't touch i_dio_count in dax_do_io() Waiman Long
2016-05-05 14:16 ` Jan Kara
2016-05-05 14:27 ` Christoph Hellwig
2016-05-05 15:48 ` Jan Kara
2016-04-29 16:27 ` [PATCH v5 2/2] ext4: Make cache hits/misses per-cpu counts Waiman Long
2016-05-05 14:03 ` Jan Kara
2016-04-29 16:38 ` [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-05-01 17:28 ` Christoph Hellwig
2016-05-02 17:45 ` Waiman Long
2016-05-05 1:57 ` Dave Chinner
2016-05-05 14:19 ` Christoph Hellwig [this message]
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