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Re: Updated zerocopy patch up on kernel.org

To: mingo@xxxxxxx
Subject: Re: Updated zerocopy patch up on kernel.org
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Wed, 10 Jan 2001 20:33:16 -0800
Cc: jgarzik@xxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.30.0101111138540.981-100000@e2> (message from Ingo Molnar on Thu, 11 Jan 2001 11:41:30 +0100 (CET))
References: <Pine.LNX.4.30.0101111138540.981-100000@e2>
Sender: owner-netdev@xxxxxxxxxxx
   Date: Thu, 11 Jan 2001 11:41:30 +0100 (CET)
   From: Ingo Molnar <mingo@xxxxxxx>

   On Tue, 9 Jan 2001, David S. Miller wrote:

   > I'm actually considering making the SG w/o hwcsum situation illegal.

   i believe it might still make some limited sense for normal sendmsg()
   and higher MTUs (or 8k NFS) - we could copy & checksum stuff into the
   ->tcp_page if SG is possible and thus the SG capability improves the VM.
   (because we can allocate at PAGE_SIZE granularity.)

Basically what your advocating for is to take advantage of SG-only
devices when we have full control of the page contents.

Sure this would work.

But honestly the real gain from SG-only devices would be (as you know)
the memory usage savings when sending a single static file object to
several thousand clients.

Later,
David S. Miller
davem@xxxxxxxxxx

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