Subject: Re: Experimental zero-copy for TCP and UDP transmit-side
To: Sean Davis <>
From: Tomas Svensson <>
List: current-users
Date: 05/10/2002 12:00:28
Friday, May 10, 2002, 10:23:29 AM, you wrote:

SD> Very nice!
SD> I enabled it on my main NetBSD/i386 server, which has a thunderlan 10/100
SD> adapter, and performance with FTP increased greatly. I typically saw 30-50mbit/s
SD> when transferring large files from it via FTP, but since adding SOSEND_LOAN,
SD> I've seen 90mbit/s more than once. I like it! :)

SD> [note: using lukemftpd on the netbsd side, ws_ftp on the windows side. don't
SD> know how accurate ws_ftp's transfer speed calculation is, but the improvement
SD> has been signifigant.]

lukemftpd can't utilize zero-copy by default? It's not using mmap()
and it's overwriting it's buffer immediately after write() returns.

I started to change ftpd into using mmap() but it made the kernel crash
(only if I used SOSEND_LOAN).