AMD64 much slower than i386 on FreeBSD 5.4-pre

[em1897 at aol.com]

I think the point of a list is so that someone can say "oh yes, I had 
problems with the
em driver in amd64 also; try card X." But instead you get a lot of 
people with no real
idea trying to explain away the problem, as if there is no chance that 
the amd64
implementant just plain sucks wind. If someone who actually has an 
amd64 build
could post some usage/load numbers, or someone who did some testing 
with
various hardware, that might be useful.  So far what we have is like a 
bunch of
Mothers trying to defend their children without having any viable 
answers or
evidence than amd64 is any good at all. Only a people who say 
nonsensical
things like "my opteron blows away any P4", like a kid bragging about 
his
mustang or something.

The em driver has a standard hold-off of 8000 ints/second, so thats not 
likely
the problem. Its likely to be the same in both i386 and amd64, so its a
control.


<snippage> 
So the whole interrupt/process switching mechanism runs like crap with 
the amd64 build? Since I don't have a amd64 system, and you might hav 
access to atleast 1, how about getting a little info on the irqs? Look 
at systat -vmstat or vmstat -i under load? aybe report it back? I 
wonder if the irq rates are changing, or irqs are taking longer to 
service. Either there is a problem. Ofcourse some hardware info would 
be nice, chipset and cpu? Maybe you script vmstat -i for a log, and use 
netperf too?  
I like Nick's followup. I would guese Boris may have a problem with 
proper hardware support. I can't really said it is bad hardware if 
speeds are the same, just high load(right?). Maybe the driver he is 
using is not good for 64bit as it is for 32bit? 
 
I think if Boris studies the thread I like to below he will be alright. 
 
Check this out: 
http://www.atm.tut.fi/list-archive/freebsd-stable/thrd66.html 
http://docs.freebsd.org/cgi/mid.cgi?200502171636.10361.drice 
 
Inparticular: 
http://www.atm.tut.fi/list-archive/freebsd-stable/msg19651.html 
http://www.atm.tut.fi/list-archive/freebsd-stable/msg19679.html 
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