Subject: Re: BCM5704 performance questions.

From: "Michael Chan" <[email-masked]>
Date: Thu, 09 Jun 2005 17:37:41 -0700

On Thu, 2005-06-09 at 18:24 -0700, Ben Greear wrote:
> Michael Chan wrote:
> > 
> > Unfortunately, the 5704 requires the "ONE_DMA" workaround which will
> > limit throughput in a PCIX 100/133 bus. If you comment out the line that
> > sets the DMA_RWCTRL_ONE_DMA flag in tg3.c, you should see improved
> > performance. However, you may run into some DMA issues on certain
> > systems.
> 
> Is there any way I can tell which systems are affected?  It won't be
> an option for me to purposefully ship possibly busted drivers/hardware,
> but if I can be certain that my systems are immune, I will try this
> modification.
> 
I mentioned this so that you could verify that the slow performance was
indeed caused by ONE_DMA. Even if your system is affected, it's a very
subtle problem that won't show up right away and should allow you to get
some performance numbers.

Unfortunately, if indeed it is ONE_DMA, there is no easy way for us to
tell which system is affected. And the recommendation is to turn it on
for all 5704 in PCIX 100/133.