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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <4EDC79DC-0C32-40FD-9C35-164C7A077922@oracle.com> References: <4EDC79DC-0C32-40FD-9C35-164C7A077922@oracle.com> <20230316152618.711970-1-dhowells@redhat.com> <20230316152618.711970-28-dhowells@redhat.com> <3DFBF27C-A62B-4AFE-87FD-3DF53FC39E8E@hammerspace.com> To: Chuck Lever III Cc: dhowells@redhat.com, Trond Myklebust , Matthew Wilcox , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Al Viro , Christoph Hellwig , Jens Axboe , Jeffrey Layton , Christian Brauner , Linus Torvalds , "netdev@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Anna Schumaker , Linux NFS Mailing List Subject: Re: [RFC PATCH 27/28] sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <782775.1678987682.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 16 Mar 2023 17:28:02 +0000 Message-ID: <782776.1678987682@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Rspamd-Queue-Id: 384F3C0027 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 9ri1hs6qngpttb34ku7mdmhprm7u495f X-HE-Tag: 1678987693-919296 X-HE-Meta: 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 mwhge601 MSwDzDU3o57mBCNg3+7zyxhKMNGcV8egU5YmegDQyen+0BpK7ATLW8kTmg5HXilBIUQvBQwGSZxPmzaWeh0QkUxrZ6pPQrTMIfU1CLWVjz0kVD4E8hGWYfVoGb9v12V594yPVnEonXXeW2lTNSXclDAawscHMgw4Yho9PQ6tMtW9jDeO79U0CIQ6cb1tfgvqdxNYLD90+PpIN8jbtjr5SHEpA9/qDjkX54kCk+RhQmJjxPRetF7Do8zVGc0LbsL1Jh8pUORIK+23jO7lGJTc/wcXcY3czf6L5d9p6dRPw/N1kldLI2EkedKeen6/ZrpJa3kCO75TDmVpAbVnXKettS+8ZQ3wztZFDjI8swNxNnoXPXeyAKYDSCWJ5rw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Chuck Lever III wrote: > That means I haven't seen the cover letter and do not have any > context for this proposed change. https://lore.kernel.org/linux-fsdevel/20230316152618.711970-1-dhowells@red= hat.com/ > We've tried combining the sendpages calls in here before. It > results in a significant and measurable performance regression. > See: > = > da1661b93bf4 ("SUNRPC: Teach server to use xprt_sock_sendmsg for socket = sends") The commit replaced the use of sendpage with sendmsg, but that took away t= he zerocopy aspect of sendpage. The idea behind MSG_SPLICE_PAGES is that it allows you to do keep that. I'll have to try reapplying this commit and adding the MSG_SPLICE_PAGES flag. > Therefore, this kind of change needs to be accompanied by both > benchmark results and some field testing to convince me it won't > cause harm. Yep. > And, we have to make certain that this doesn't break operation > with kTLS sockets... do they support MSG_SPLICE_PAGES ? I haven't yet tackled AF_TLS, AF_KCM or AF_SMC as they seem significantly = more complex than TCP and UDP. I thought I'd get some feedback on what I have before I tried my hand at those. David