Return-Path: Received: from mx2.netapp.com ([216.240.18.37]:46646 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756638Ab1DMO1b (ORCPT ); Wed, 13 Apr 2011 10:27:31 -0400 Subject: Re: [RFC][PATCH] Vector read/write support for NFS (DIO) client Content-Type: text/plain; charset=us-ascii From: Andy Adamson In-Reply-To: <1302704533.8571.12.camel@lade.trondhjem.org> Date: Wed, 13 Apr 2011 10:27:23 -0400 Cc: Jeff Layton , Badari Pulavarty , Chuck Lever , linux-nfs@vger.kernel.org, khoa@us.ibm.com Message-Id: <00D863C6-8B7E-4645-A53E-14D1E2507AEE@netapp.com> References: <1302622335.3877.62.camel@badari-desktop> <0DC51758-AE6C-4DD2-A959-8C8E701FEA4E@oracle.com> <1302624935.3877.66.camel@badari-desktop> <1302630360.3877.72.camel@badari-desktop> <20110413083656.12e54a91@tlielax.poochiereds.net> <4DA5A899.3040202@us.ibm.com> <20110413100228.680ace66@tlielax.poochiereds.net> <1302704533.8571.12.camel@lade.trondhjem.org> To: Trond Myklebust Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Apr 13, 2011, at 10:22 AM, Trond Myklebust wrote: > On Wed, 2011-04-13 at 10:02 -0400, Jeff Layton wrote: >> We could put the rpc_rqst's into a slabcache, and give each rpc_xprt a >> mempool with a minimum number of slots. Have them all be allocated with >> GFP_NOWAIT. If it gets a NULL pointer back, then the task can sleep on >> the waitqueue like it does today. Then, the clients can allocate >> rpc_rqst's as they need as long as memory holds out for it. >> >> We have the reserve_xprt stuff to handle congestion control anyway so I >> don't really see the value in the artificial limits that the slot table >> provides. >> >> Maybe I should hack up a patchset for this... > > This issue has come up several times recently. My preference would be to > tie the availability of slots to the TCP window size, and basically say > that if the SOCK_ASYNC_NOSPACE flag is set on the socket, then we hold > off allocating more slots until we get a ->write_space() callback which > clears that flag. I am scoping the dynamic rpc_slot allocation work and plan to prototype. -->Andy > > For the RDMA case, we can continue to use the current system of a fixed > number of preallocated slots. > > Cheers > Trond > -- > Trond Myklebust > Linux NFS client maintainer > > NetApp > Trond.Myklebust@netapp.com > www.netapp.com > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html