Subject: RE: zbufs for NetBSD
To: None <>
From: Bill Studenmund <>
List: tech-kern
Date: 09/06/2002 17:46:54
On Fri, 6 Sep 2002 wrote:

> Recieving and transmitting large volumes of data is where zbufs would be a
> help.  NetBSD on large data transmits of memory mapped files does a minimal
> amount of coping, but recieving large amounts of data is another question.
> Does NetBSD perform the same way when receiving data from the network to a
> memory mapped file?
> When recieving data that is measured in megabytes per second, and with
> networks moving to 10 Megabytes (100Mbit/sec) to 100 Megabytes
> (1000Mbits/sec), it would seem that doing a zero copy recieve would be
> advantageous.   Preallocating recieve buffers and managing VM tables would
> seem a faster solution than memcpy when dealing with megabytes/sec data
> speeds.

I think the better question is, what do you want? Do you really want
zbufs, or do you want zero-copy receive and think that zbufs are a
convenient way to do that. Because if a developer doesn't like zbuffs (I
know Jason's the only one who's spoken, but I don't know what other folks
think), that doesn't mean we don't want zero-copy receive. It could just
be that zbuffs aren't a good fit for zcr for us, and we need to do
something else.

Take care,