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From: keith.busch@intel.com (Keith Busch)
Subject: [PATCH 8/9] nvme: implement multipath access to nvme subsystems
Date: Mon, 25 Sep 2017 10:45:35 -0400	[thread overview]
Message-ID: <20170925144535.GB6331@localhost.localdomain> (raw)
In-Reply-To: <55a10165-ac3c-f808-b031-6d907c314c30@suse.de>

On Mon, Sep 25, 2017@04:05:17PM +0200, Hannes Reinecke wrote:
> On 09/25/2017 03:50 PM, Christoph Hellwig wrote:
> > On Mon, Sep 25, 2017@03:47:43PM +0200, Hannes Reinecke wrote:
> >> Can't we make the multipath support invisible to the host?
> >> IE check the shared namespaces before creating the device node, and just
> >> move them under the existing namespaces if one exists?
> > 
> > That was what my first version did, but various people talked me
> > out of it.  Unfortunately just multiplexing breaks a few things,
> > including the userspace passthrough ioctls.
> > 
> Care to give some specifics?
> How would userspace passthrough be affected?

Ioctls aside, if you've only one disk handle, it's a little difficult to
compare iostats on each path, which can be useful for diagnosing issues.

> I would've thought that we're sending the ioctl down one path, and we'd
> be getting the completion back on the same path/queue/whatever.
> (Unless we're talking multi-command ioctls, but those are evil anyway)

  reply	other threads:[~2017-09-25 14:45 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-25 13:40 nvme multipath support V3 Christoph Hellwig
2017-09-25 13:40 ` [PATCH 1/9] block: move REQ_NOWAIT Christoph Hellwig
2017-10-11 11:51   ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 2/9] block: add REQ_DRV bit Christoph Hellwig
2017-10-11 11:51   ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 3/9] block: provide a direct_make_request helper Christoph Hellwig
2017-10-11 11:54   ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 4/9] block: add a blk_steal_bios helper Christoph Hellwig
2017-09-25 13:40 ` [PATCH 5/9] nvme: track subsystems Christoph Hellwig
2017-09-25 16:07   ` Keith Busch
2017-10-11 11:57   ` Sagi Grimberg
2017-10-18 10:12     ` Christoph Hellwig
2017-10-18 11:16       ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 6/9] nvme: introduce a nvme_ns_ids structure Christoph Hellwig
2017-09-25 16:08   ` Keith Busch
2017-10-11 11:59   ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 7/9] nvme: track shared namespaces Christoph Hellwig
2017-09-25 16:11   ` Keith Busch
2017-09-25 16:19     ` Christoph Hellwig
2017-10-11 12:04   ` Sagi Grimberg
2017-10-18 10:15     ` Christoph Hellwig
2017-09-25 13:40 ` [PATCH 8/9] nvme: implement multipath access to nvme subsystems Christoph Hellwig
2017-09-25 13:47   ` Hannes Reinecke
2017-09-25 13:50     ` Christoph Hellwig
2017-09-25 14:05       ` Hannes Reinecke
2017-09-25 14:45         ` Keith Busch [this message]
2017-09-25 15:07         ` Christoph Hellwig
2017-09-25 16:18   ` Keith Busch
2017-09-28 15:53   ` Keith Busch
2017-09-29 14:21     ` Tony Yang
2017-10-01  8:07       ` Christoph Hellwig
2017-09-30 19:37     ` Johannes Thumshirn
2017-10-01  8:07       ` Christoph Hellwig
2017-10-02  6:19       ` Hannes Reinecke
2017-10-11 12:24   ` Sagi Grimberg
2017-09-25 13:40 ` [PATCH 9/9] nvme: also expose the namespace identification sysfs files for mpath nodes Christoph Hellwig
2017-09-25 16:19   ` Keith Busch

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