Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:16516 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932625AbbGJTeJ convert rfc822-to-8bit (ORCPT ); Fri, 10 Jul 2015 15:34:09 -0400 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: [PATCH v1 02/12] xprtrdma: Raise maximum payload size to one megabyte From: Chuck Lever In-Reply-To: <55A01B56.2020107@Netapp.com> Date: Fri, 10 Jul 2015 15:33:55 -0400 Cc: linux-rdma@vger.kernel.org, Linux NFS Mailing List Message-Id: References: <20150709203242.26247.4848.stgit@manet.1015granger.net> <20150709204159.26247.44592.stgit@manet.1015granger.net> <55A01B56.2020107@Netapp.com> To: Anna Schumaker Sender: linux-nfs-owner@vger.kernel.org List-ID: On Jul 10, 2015, at 3:21 PM, Anna Schumaker wrote: > Hi Chuck, > > On 07/09/2015 04:41 PM, Chuck Lever wrote: >> The point of larger rsize and wsize is to reduce the per-byte cost >> of memory registration and deregistration. Modern HCAs can typically >> handle a megabyte or more with a single registration operation. >> >> Signed-off-by: Chuck Lever >> --- >> net/sunrpc/xprtrdma/xprt_rdma.h | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h >> index f49dd8b..abee472 100644 >> --- a/net/sunrpc/xprtrdma/xprt_rdma.h >> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h >> @@ -165,8 +165,7 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb) >> * struct rpcrdma_buffer. N is the max number of outstanding requests. >> */ >> >> -/* temporary static scatter/gather max */ >> -#define RPCRDMA_MAX_DATA_SEGS (64) /* max scatter/gather */ >> +#define RPCRDMA_MAX_DATA_SEGS ((1 * 1024 * 1024) / PAGE_SIZE) > ^^^ > What is the significance of the 1 here? This echoes the definition of RPCSVC_MAXPAYLOAD. ?1? documents ?one? megabyte, I assume. > Thanks, > Anna > >> #define RPCRDMA_MAX_SEGS (RPCRDMA_MAX_DATA_SEGS + 2) /* head+tail = 2 */ >> >> struct rpcrdma_buffer; >> >> -- >> 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 >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever