Return-Path: Received: from mx143.netapp.com ([216.240.21.24]:18359 "EHLO mx143.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932579AbbGJTlc (ORCPT ); Fri, 10 Jul 2015 15:41:32 -0400 Subject: Re: [PATCH v1 02/12] xprtrdma: Raise maximum payload size to one megabyte To: Chuck Lever References: <20150709203242.26247.4848.stgit@manet.1015granger.net> <20150709204159.26247.44592.stgit@manet.1015granger.net> <55A01B56.2020107@Netapp.com> CC: , Linux NFS Mailing List From: Anna Schumaker Message-ID: <55A01FE9.8000309@Netapp.com> Date: Fri, 10 Jul 2015 15:41:29 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: On 07/10/2015 03:33 PM, Chuck Lever wrote: > > 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. > > β€œ1” documents β€œone” megabyte, I assume. Makes sense. Thanks! > > >> 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 > > >