pf + ftp throughput

Darrin Chandler dwchandler at
Fri Jun 16 19:27:36 UTC 2006

On Fri, Jun 16, 2006 at 02:13:00PM -0500, J.D. Bronson wrote:
> At 02:10 PM 6/16/2006, Darrin Chandler wrote:
> >On Fri, Jun 16, 2006 at 01:59:01PM -0500, J.D. Bronson wrote:
> >> For example...moving a 50MB file:
> >>
> >> 'keep state' = 11-12MB/sec over 100MB-FDX
> >> 'modulate state = 6-7MB/sec over 100MB-FDX
> >>
> >> took me a while to determine the culprit here - but I am curious
> >> as to why this is the case?
> >
> >Since modulate state substitues its own high quality random sequence for
> >the TCP stream in both directions, a wimpy CPU or similar problem could
> >easily cause this, I think. Still, I'm surprised to see a 50% hit from
> >using modulate state.
> Yes. I am too!
> This is a P4-3.06 with 1GB ram...under almost no I cant 
> fault the CPU this time....

The only two things that come to mind are 1) pf is using a really
complex and slow random source, or 2) something is going haywire with
the connection.

Have your tried tcpdump on either interface (not pflog) to see if
anything strange is going on (ACK storms, etc)? Just fishing at this

Darrin Chandler            |  Phoenix BSD Users Group
dwchandler at   |  |

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