From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: RCU-ified dm-mpath for testing/review Date: Mon, 15 Feb 2016 07:47:35 +0100 Message-ID: <56C17487.7050301@suse.de> References: <20160207172055.GA6477@redhat.com> <56B99A49.5050400@suse.de> <20160209145547.GA21623@redhat.com> <56BA0689.9030007@suse.de> <20160210004518.GA23646@redhat.com> <20160211015030.GA4481@redhat.com> <20160211153452.GA7827@redhat.com> <56BDF7D7.8040106@suse.de> <20160212152651.GB11104@redhat.com> <56BE0295.4090809@suse.de> <20160212180032.GA14013@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20160212180032.GA14013@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer Cc: "axboe@kernel.dk" , "keith.busch@intel.com" , Christoph Hellwig , Sagi Grimberg , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , device-mapper development , Bart Van Assche List-Id: dm-devel.ids On 02/12/2016 07:00 PM, Mike Snitzer wrote: > On Fri, Feb 12 2016 at 11:04am -0500, > Hannes Reinecke wrote: > = >> On 02/12/2016 04:26 PM, Mike Snitzer wrote: >>> On Fri, Feb 12 2016 at 10:18am -0500, >>> Hannes Reinecke 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=3D= devel3 >>> >>> Also, please read this header: >>> http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h= =3Ddevel3&id=3D65a01b76502dd68e8ca298ee6614c0151b677f4a >>> >>> 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). > = Fully understood. But as I said, the _need_ for repeat_count has essentially vanished with the move to request-based multipath. > As such I've rebased 'devel3' to impose repeat_count =3D 1 (both in > dm-mpath.c and the defaults in each path selector). Kewl. I'll give it a go. Cheers, Hannes -- = Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: F. Imend=F6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=FCrnberg) From mboxrd@z Thu Jan 1 00:00:00 1970 From: hare@suse.de (Hannes Reinecke) Date: Mon, 15 Feb 2016 07:47:35 +0100 Subject: RCU-ified dm-mpath for testing/review In-Reply-To: <20160212180032.GA14013@redhat.com> References: <20160207172055.GA6477@redhat.com> <56B99A49.5050400@suse.de> <20160209145547.GA21623@redhat.com> <56BA0689.9030007@suse.de> <20160210004518.GA23646@redhat.com> <20160211015030.GA4481@redhat.com> <20160211153452.GA7827@redhat.com> <56BDF7D7.8040106@suse.de> <20160212152651.GB11104@redhat.com> <56BE0295.4090809@suse.de> <20160212180032.GA14013@redhat.com> Message-ID: <56C17487.7050301@suse.de> On 02/12/2016 07:00 PM, Mike Snitzer wrote: > On Fri, Feb 12 2016 at 11:04am -0500, > Hannes Reinecke wrote: > >> On 02/12/2016 04:26 PM, Mike Snitzer wrote: >>> On Fri, Feb 12 2016 at 10:18am -0500, >>> Hannes Reinecke 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). > Fully understood. But as I said, the _need_ for repeat_count has essentially vanished with the move to request-based multipath. > As such I've rebased 'devel3' to impose repeat_count = 1 (both in > dm-mpath.c and the defaults in each path selector). Kewl. I'll give it a go. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare at suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg GF: F. Imend?rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N?rnberg)