Subject: Re: Experimental zero-copy for TCP and UDP transmit-side
To: Wolfgang Rupprecht <>
From: Jason R Thorpe <>
List: current-users
Date: 05/08/2002 17:44:32
On Wed, May 08, 2002 at 05:40:45PM -0700, Wolfgang Rupprecht wrote:

 > In the sliding window case, is it safe to unmap() the old window's
 > pages while the network write is still going on?

Yes.  The kernel has its own mapping, and the page will still be
owned by the backing object.

 > Lets say one wants to copy a raw disk across the network.  With
 > today's disks that will take quite a few max sized mmap() windows.
 > Would the zero copy case still be used if one were to write a window
 > sized hunk, slide the window and write() again in a tight loop?

Yes, that should work just fine.

        -- Jason R. Thorpe <>