Subject: Re: ex driver performance
To: RJ45 <>
From: Martin Husemann <>
List: port-sparc64
Date: 02/12/2003 23:29:00
On Wed, Feb 12, 2003 at 03:21:50PM -0700, RJ45 wrote:

> I noticed that performance on this interface are poor compared to hme0.
> my hme0 performs at 8MB/s while ex0 (3com 905) performa at 4MB/s

Yeah, I have a hme0 and a vr0, and while the hme0 can saturate the wire,
the vr0 is bound to ~4MB/s.

This is not fully analyzed, but it is related to the IOMMU usage and support
routines in the sparc64 port. The hme driver handles dma maps "special",
thus avoiding a lot of IOMMU operations.

I consider the slow dma map operations a bug, that needs to be fixed.
(Assuming this is the real cause - someone needs to profile the kernel and