On 02/12/2016 04:26 PM, Mike Snitzer wrote:
On Fri, Feb 12 2016 at 10:18am -0500,
Hannes Reinecke <hare@xxxxxxx> wrote:
On 02/11/2016 04:34 PM, Mike Snitzer wrote:
On Wed, Feb 10 2016 at 8:50pm -0500,
Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
On Tue, Feb 09 2016 at 7:45pm -0500,
Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
OK, I took a crack at embracing RCU. Only slightly better performance
on my single NUMA node testbed. (But I'll have to track down a system
with multiple NUMA nodes to do any justice to the next wave of this
optimization effort)
This RCU work is very heavy-handed and way too fiddley (there could
easily be bugs). Anyway, please see:
http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h=devel2&id=d80a7e4f8b5be9c81e4d452137623b003fa64745
But this might give you something to build on to arrive at something
more scalable?
I've a bit more polished version of this work (broken up into multiple
commits, with some fixes, etc) here:
http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel3
Hannes and/or Sagi, if you get a chance to try this on your NUMA system
please let me know how it goes.
Initial review has uncovered some locking problems with the current code
(nothing that caused crashes or hangs in my testing but...) so please
hold off on testing until you hear from me (hopefully tomorrow).
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.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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