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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: References: <20230623225513.2732256-1-dhowells@redhat.com> <20230623225513.2732256-5-dhowells@redhat.com> <3070989.1687793422@warthog.procyon.org.uk> To: Ilya Dryomov Cc: dhowells@redhat.com, netdev@vger.kernel.org, Alexander Duyck , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiubo Li , Jeff Layton , ceph-devel@vger.kernel.org Subject: Re: [PATCH net-next v5 04/16] ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3085214.1687798916.1@warthog.procyon.org.uk> Date: Mon, 26 Jun 2023 18:01:56 +0100 Message-ID: <3085215.1687798916@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Stat-Signature: zhio86rp76e7cpy548imsekqmun6uk7e X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: C16011C0073 X-Rspam-User: X-HE-Tag: 1687798979-152779 X-HE-Meta: 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 +M8KoEWp pzXo1kdnUQCbTNvMTToHZtcz34g0XsDXTrUUrIA9jeenyNe/rLviLkoG7HvQIblXYeGmzqYEhisLb8Wi+vsVqlcOFQ2X/2bVu7a4ODZ+kz+/N+soNmu+J2CT5A/3bz1BVKCY6uTa4iKQj+pTtEhuHwD1ycFtz0Xq/h1BTBNHU54yxRHVlwuUFVManzx+i1dD5Urm06Dme1r7781Of49wcsqhY2vzy9FDKg9yDrgWPnRvw7mnQIwIksShv5AGEjYGaeEumbDb2cMH3B6aepgsufAZKdoYgFXXfCGqPAu6dCrXuuNo= 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: Ilya Dryomov wrote: > > Btw, is it feasible to use con->v2.out_iter_sendpage to apply > > MSG_SPLICE_PAGES to the iterator to be transmitted as a whole? It seems > > to be set depending on iterator type. > > I'm not sure I understand what you mean by "transmitted as a whole". > con->v2.out_iter_sendpage is set only when zerocopy is desired. If the > underlying data is not guaranteed to remain stable, zerocopy behavior > is not safe. I think I need to reinstate the per-page sendpage_ok() check here also - though Al pointed out it isn't sufficiently exhaustive. There are pages that sendpage_ok() will return true on that you shouldn't be passing to sendpage(). I'll whip up a patch to partially revert this also. David