From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH 9/9] IB/srp: Add fast registration support Date: Thu, 08 May 2014 14:38:22 +0200 Message-ID: <536B7ABE.8080502@acm.org> References: <5368DA5B.80609@acm.org> <5368DC09.70608@acm.org> <536A1A3A.9090208@dev.mellanox.co.il> <536A4A68.4080605@acm.org> <536A6B2F.70807@dev.mellanox.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <536A6B2F.70807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sagi Grimberg , Roland Dreier Cc: Sagi Grimberg , Vu Pham , David Dillow , Sebastian Parschauer , linux-rdma List-Id: linux-rdma@vger.kernel.org On 05/07/14 19:19, Sagi Grimberg wrote: > On 5/7/2014 5:59 PM, Bart Van Assche wrote: >> On 05/07/14 13:34, Sagi Grimberg wrote: >>>> + pool = srp_create_fr_pool(dev->dev, dev->pd, >>>> + SRP_MDESC_PER_POOL, max_pages_per_mr); >>> 1024 FRMRs per connection?! we use 1024 FMRs for all connections >>> (per-device). I'd say that's a major over-allocation. >> It depends on how many discontiguous I/O requests are submitted >> concurrently. Anyway, how about limiting the number of memory regions to >> the queue size ? > > Perhaps, but we will need to reserve some more for discontinuous IOs. > It is heuristic, for FS in most cases IO will align nicely, for some > crazy DB applications - I'm not sure. If srp_map_sg() runs out of memory descriptors it adds the remaining sg entries to the SRP indirect descriptor without using memory registration. In other words, I think a queue full of discontiguous I/O requests should be handled properly by srp_map_sg(). Bart. -- 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