linux-kernel - Re: [RFC PATCH v2 40/48] sunrpc: Use sendmsg(MSG_SPLICE

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Message-ID: <777295.1680168547@warthog.procyon.org.uk>
Date:   Thu, 30 Mar 2023 10:29:07 +0100
From:   David Howells <dhowells@...hat.com>
To:     Chuck Lever III <chuck.lever@...cle.com>
Cc:     dhowells@...hat.com, Matthew Wilcox <willy@...radead.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna@...nel.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: [RFC PATCH v2 40/48] sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

Chuck Lever III <chuck.lever@...cle.com> wrote:

> It seems to me that you could eliminate the kernel_sendpage()
> consumer here in svc_tcp_sendmsg() without also replacing the
> kernel_sendmsg() calls. That would be a conservative step-wise
> approach which would carry less risk, and would accomplish
> your stated goal without more radical surgery.

Note that only the marker is sent with kernel_sendmsg() in the unmodified
code; the head and tail are sent with svc_tcp_send_kvec()... which uses
kernel_sendpage() which needs to be changed in my patchset.  I can make it do
individual sendmsg calls for all those for now.

David