[openib-general] [PATCH] ipoib tune rx ring size

[Grant Grundler]

On Mon, Jun 20, 2005 at 03:52:11PM -0400, William Jordan wrote:
> When receiving UDP traffic on a slow host (no user level end to end
> flow control), you can improve receive throughput by reducing the
> number of outstanding receives. The CPU can be saturated receiving
> packets which are overflowing the socket (being discarded), and the
> user can be CPU starved (unable to empty the socket).

Hrm, I thought Linux's NAPI avoids this problem.
Jamal gave an excellent talk on this issue a few years ago:
	http://lwn.net/2000/0928/a/fast-forwarding.php3

I was thinking of a HW config issue.
But I want to hear what Michael has to say before tainting
the waters with other issues.

> This is not a real world situation, though.

It's very real. That's what DoS attacks are about.
It just not expected on a private network with trusted hosts.

grant