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Re: [PLEASE-TESTME] Zerocopy networking patch, 2.4.0-1

To: hch@xxxxxxxxxx
Subject: Re: [PLEASE-TESTME] Zerocopy networking patch, 2.4.0-1
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Tue, 9 Jan 2001 02:31:13 -0800
Cc: mingo@xxxxxxx, riel@xxxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <20010109113145.A28758@caldera.de> (message from Christoph Hellwig on Tue, 9 Jan 2001 11:31:45 +0100)
References: <Pine.LNX.4.21.0101081603080.21675-100000@duckman.distro.conectiva> <Pine.LNX.4.30.0101091051460.1159-100000@e2> <20010109113145.A28758@caldera.de>
Sender: owner-netdev@xxxxxxxxxxx
   Date: Tue, 9 Jan 2001 11:31:45 +0100
   From: Christoph Hellwig <hch@xxxxxxxxxx>

   Yuck.  A new file_opo just to get a few benchmarks right ...  I
   hope the writepages stuff will not be merged in Linus tree (but I
   wish the code behind it!)

It's a "I know how to send a page somewhere via this filedescriptor
all by myself" operation.  I don't see why people need to take
painkillers over this for 2.4.x.  I think f_op->write is stupid, such
a special case file operation just to get a few benchmarks right.
This is the kind of argument I am hearing.

Orthogonal to f_op->write being for specifying a low-level
implementation of sys_write, f_op->writepage is for specifying a
low-level implementation of sys_sendfile.  Can you grok that?

Linus has already seen this.  Originally he had a gripe because in an
older revision of the code used to allow multiple pages to be passed
in an array to the writepage(s) operation.  He didn't like that, so I
made it take only one page as he requested.  He had no other major
objections to the infrastructure.

Later,
David S. Miller
davem@xxxxxxxxxx

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