From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 8/8] IB/srp: Make queue size configurable Date: Wed, 21 Aug 2013 10:19:36 +0300 Message-ID: <52146A08.8090802@mellanox.com> References: <521363EA.8080906@acm.org> <52136609.3090406@acm.org> <52138C6E.6080201@mellanox.com> <5213917B.3020403@acm.org> <1377020595.22321.6.camel@frustration.ornl.gov> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1377020595.22321.6.camel-zHLflQxYYDO4Hhoo1DtQwJ9G+ZOsUmrO@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Dillow Cc: Bart Van Assche , Roland Dreier , Vu Pham , Sebastian Riemer , linux-rdma , Konrad Grzybowski List-Id: linux-rdma@vger.kernel.org On 8/20/2013 8:43 PM, David Dillow wrote: > On Tue, 2013-08-20 at 17:55 +0200, Bart Van Assche wrote: >> On 08/20/13 17:34, Sagi Grimberg wrote: >>> Question, >>> If srp now will allow larger queues while using a single global FMR pool >>> of size 1024, isn't it more likely now that in stress environment srp >>> will run out of FMRs to handle IO commands? >>> I mean that let's say that you have x scsi hosts with can_queue size of >>> 512 (+-) and all of them are running IO stress, is it possible that all >>> FMRs will be inuse and no FMR is available to register the next IO SG-list? >>> Did you try out such a scenario? >>> >>> I guess that in such a case IB core will return EAGAIN and SRP will >>> return SCSI_MLQUEUE_HOST_BUSY. >>> I think it is a good Idea to move FMR pools to be per connection rather >>> than a global pool, what do you think? >> That makes sense to me. And as long as the above has not yet been >> implemented I'm fine with dropping patch 8/8 from this patch set. > Don't drop it; most configs won't have all that many connections and > shouldn't have an issue; even those that do will only see a potential > slowdown when running with everything at once. > > We can address the FMR/BMME issues on top of this patch. Agree. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html