On Tue, 10 Jun 2003, David S. Miller wrote: > Acutally, the main issue with 3c59x is that it still > uses PIO accesses. This basically makes it useless > for routing or anything wanting serious latency. I did try about 2 years ago and converted the driver to MMIO. I wasn't able to see _any_ kind of improvement and I was using it in parallel computation where latency counts. I have to say though that I wasn't interested at that time in obtaining profiles and such because only the end-user performance was important. > Andrew Morton knows this, ... and knows about my MMIO trial too (mentioned also on vortex-list)... > but he is such a good maintainer that he doesn't want to change over the > MEM I/O accesses for fear of breaking something. Given that the 3c59x driver supports several generations of cards most of them being EOL-ed years ago, it's pretty hard to do such change. If a new driver would be forked that serviced only the latest generations (Cyclone = 905B and Tornado = 905C(X)), switching to MMIO would probably make sense along with lots of others small changes (large MTU/VLAN, polling descriptors, MII-only media selection etc.) and maybe have NAPI in the mix as well... > It's actually a simple change to make if someone wants to > spend a few cycles on it, Not if you include testing in those cycles :-) -- Bogdan Costescu IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868 E-mail: Bogdan.Costescu@IWR.Uni-Heidelberg.De - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
