From: Mike Snitzer <snitzer@redhat.com>
To: Hannes Reinecke <hare@suse.de>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
"keith.busch@intel.com" <keith.busch@intel.com>,
Christoph Hellwig <hch@infradead.org>,
Sagi Grimberg <sagig@dev.mellanox.co.il>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
device-mapper development <dm-devel@redhat.com>,
Bart Van Assche <bart.vanassche@sandisk.com>
Subject: Re: RCU-ified dm-mpath for testing/review
Date: Fri, 12 Feb 2016 13:00:32 -0500 [thread overview]
Message-ID: <20160212180032.GA14013@redhat.com> (raw)
In-Reply-To: <56BE0295.4090809@suse.de>
On Fri, Feb 12 2016 at 11:04am -0500,
Hannes Reinecke <hare@suse.de> wrote:
> On 02/12/2016 04:26 PM, Mike Snitzer wrote:
> >On Fri, Feb 12 2016 at 10:18am -0500,
> >Hannes Reinecke <hare@suse.de> wrote:
> >>>
> >>Good news is that I've managed to hit the roof for my array with the
> >>devel2 version of those patches. (And a _heavily_ patched-up lpfc
> >>driver :-)
> >>So from that perspective everything's fine now; we've reached the
> >>hardware limit for my setup.
> >>Which in itself is quite impressive; beating Intel P3700 with 16FC
> >>is not bad methinks :-)
> >>
> >>So thanks for all your work here.
> >
> >Ah, that's really good news! But devel2 is definitely _not_ destined
> >for upstream. 'devel3' is much closer to "ready". But your testing and
> >review would really push it forward.
> >
> >Please see/test:
> >http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel3
> >
> >Also, please read this header:
> >http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h=devel3&id=65a01b76502dd68e8ca298ee6614c0151b677f4a
> >
> >Even with devel2 I hacked it such that repeat_count > 1 is effectively
> >broken. I'm now _seriously_ considering deprecating repeat_count
> >completely (adding a DMWARN that will inform the user. e.g.:
> >"repeat_count > 1 is no longer supported"). I see no point going to
> >great lengths to maintain a dm-mpath feature that was only a hack for
> >when dm-mpath was bio-based. What do you think?
>
> Drop it, and make setting of which a no-op.
> Never liked it anyway, and these decisions should really be
> delegated to the path selector.
Sure, but my point is DM-mpath will no longer be able to provide the
ability to properly handle repeat_count > 1 (because updating the
->current_pgpath crushes the write-side of the RCU).
As such I've rebased 'devel3' to impose repeat_count = 1 (both in
dm-mpath.c and the defaults in each path selector).
next prev parent reply other threads:[~2016-02-12 18:00 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <569CD4D6.2040908@dev.mellanox.co.il>
2016-01-19 10:37 ` dm-multipath low performance with blk-mq Sagi Grimberg
2016-01-19 22:45 ` Mike Snitzer
2016-01-25 21:40 ` Mike Snitzer
2016-01-25 23:37 ` Benjamin Marzinski
2016-01-26 13:29 ` Mike Snitzer
2016-01-26 14:01 ` Hannes Reinecke
2016-01-26 14:47 ` Mike Snitzer
2016-01-26 14:56 ` Christoph Hellwig
2016-01-26 15:27 ` Mike Snitzer
2016-01-26 15:57 ` Benjamin Marzinski
2016-01-27 11:14 ` Sagi Grimberg
2016-01-27 17:48 ` Mike Snitzer
2016-01-27 17:51 ` Jens Axboe
2016-01-27 18:16 ` Mike Snitzer
2016-01-27 18:26 ` Jens Axboe
2016-01-27 19:14 ` Mike Snitzer
2016-01-27 19:50 ` Jens Axboe
2016-01-27 17:56 ` Sagi Grimberg
2016-01-27 18:42 ` Mike Snitzer
2016-01-27 19:49 ` Jens Axboe
2016-01-27 20:45 ` Mike Snitzer
2016-01-29 23:35 ` Mike Snitzer
2016-01-30 8:52 ` Hannes Reinecke
2016-01-30 19:12 ` Mike Snitzer
2016-02-01 6:46 ` Hannes Reinecke
2016-02-03 18:04 ` Mike Snitzer
2016-02-03 18:24 ` Mike Snitzer
2016-02-03 19:22 ` Mike Snitzer
2016-02-04 6:54 ` Hannes Reinecke
2016-02-04 13:54 ` Mike Snitzer
2016-02-04 13:58 ` Hannes Reinecke
2016-02-04 14:09 ` Mike Snitzer
2016-02-04 14:32 ` Hannes Reinecke
2016-02-04 14:44 ` Mike Snitzer
2016-02-05 15:13 ` [RFC PATCH] dm: fix excessive dm-mq context switching Mike Snitzer
2016-02-05 18:05 ` Mike Snitzer
2016-02-05 19:19 ` Mike Snitzer
2016-02-07 15:41 ` Sagi Grimberg
2016-02-07 16:07 ` Mike Snitzer
2016-02-07 16:42 ` Sagi Grimberg
2016-02-07 16:37 ` Bart Van Assche
2016-02-07 16:43 ` Sagi Grimberg
2016-02-07 16:53 ` Mike Snitzer
2016-02-07 16:54 ` Sagi Grimberg
2016-02-07 17:20 ` Mike Snitzer
2016-02-08 12:21 ` Sagi Grimberg
2016-02-08 14:34 ` Mike Snitzer
2016-02-09 7:50 ` Hannes Reinecke
2016-02-09 14:55 ` Mike Snitzer
2016-02-09 15:32 ` Hannes Reinecke
2016-02-10 0:45 ` Mike Snitzer
2016-02-11 1:50 ` RCU-ified dm-mpath for testing/review Mike Snitzer
2016-02-11 3:35 ` Mike Snitzer
2016-02-11 15:34 ` Mike Snitzer
2016-02-12 15:18 ` Hannes Reinecke
2016-02-12 15:26 ` Mike Snitzer
2016-02-12 16:04 ` Hannes Reinecke
2016-02-12 18:00 ` Mike Snitzer [this message]
2016-02-15 6:47 ` Hannes Reinecke
2016-01-26 1:49 ` dm-multipath low performance with blk-mq Benjamin Marzinski
2016-01-26 16:03 ` Mike Snitzer
2016-01-26 16:44 ` Christoph Hellwig
2016-01-27 2:09 ` Mike Snitzer
2016-01-27 11:10 ` Sagi Grimberg
2016-01-26 21:40 ` Benjamin Marzinski
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