lkml.org 
[lkml]   [1999]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: zero-copy TCP fileserving
On Wed, 2 Jun 1999, Bjorn Wesen wrote:

> Speaking of shortcuts, what is the status of some sort of direct
> page -> skb TCP sending ?
>
> What I mean is, when tcp does a sendmsg, it shouldn't need to copy the
> actual data into the skbuf, but merely the headers, and remember a ptr to
> the data area (which would have to be locked down until the fragment is
> acked or the connection breaks, of course). Then the network driver could
> (if it supports s/g DMA) send the headers + data directly from memory.

This simple zero-copy isn't really a win on most PC hardware as it takes
about the same amount of time to do a checksum as it does to do a checksum
and copy.

A more powerful scheme is being investigated by sct and a couple others. A
related scheme worked out on FreeBSD and presented at a recent Usenix
could cache checksums, for example.

--
"Love the dolphins," she advised him. "Write by W.A.S.T.E.."


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:52    [W:7.417 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site