Zero-copy IO

Zero-copy IO

Post by East-Wes » Fri, 23 Nov 2001 18:03:11



Does the current 4.4.x FreeBSD kernel support zero-copy IO interface?
www.freebsd.org seems saying that the work is in progress but
I wonder if any one knows what is actually going.

Thanks.

 
 
 

Zero-copy IO

Post by David Malo » Sat, 24 Nov 2001 01:21:52



>Does the current 4.4.x FreeBSD kernel support zero-copy IO interface?
>www.freebsd.org seems saying that the work is in progress but
>I wonder if any one knows what is actually going.

There are some instances of where zero copy IO occurs - the
sendfile syscall is one. However, things like NFS still end
up copying data from the vmcache into mbufs.

        David.

 
 
 

Zero-copy IO

Post by East-Wes » Sat, 24 Nov 2001 19:35:15


Quote:

>>Does the current 4.4.x FreeBSD kernel support zero-copy IO interface?
>>www.freebsd.org seems saying that the work is in progress but
>>I wonder if any one knows what is actually going.

>There are some instances of where zero copy IO occurs - the
>sendfile syscall is one. However, things like NFS still end
>up copying data from the vmcache into mbufs.

Ah a good news. So the network socket interface is using zero-copy IO?
What release version of FreeBSD has this support? I cannot find any
release information regarding zero-copy IO. Thanks.

John

 
 
 

Zero-copy IO

Post by Nick Hilliar » Sat, 24 Nov 2001 19:44:40



> Ah a good news. So the network socket interface is using zero-copy IO?
> What release version of FreeBSD has this support? I cannot find any
> release information regarding zero-copy IO. Thanks.

No - the sendfile system call uses zero-copy i/o.  The normal socket interface
system calls use mbufs.

See the sendfile manual page for more information.

Nick