AMD64 much slower than i386 on FreeBSD 5.4-pre

[em1897 at aol.com]

I think that warning people that the good name of "FreeBSD" is being
tainted by the current band of clowns is very productive. Its more like
a religion now; I've never seen so many people in total denial that 
their
beliefs are completely wrong. A lot of people are wasting a lot of time
because of this propaganda. The cluelessness in the performance
list is a good indication.


-----Original Message-----
From: jason henson <jason at ec.rr.com>
To: em1897 at aol.com
Cc: freebsd-questions at freebsd.org; hardcodeharry at yahoo.com
Sent: Thu, 24 Mar 2005 00:57:58 -0500
Subject: Re: AMD64 much slower than i386 on FreeBSD 5.4-pre

em1897 at aol.com wrote: 
 
> > 
>> The answer, Boris, is that the "team" has no idea what >> they're 
doing. Check out some of the threads on >> performance testing. They 
tune little pieces here >> and there, and break 10 other things in the 
process. >> Matt Dillon "determined" that 10,000 ints/second >> was 
"optimal". Of course if you're passing 10Kpps >> that means you get an 
interrupt for every >> packet. >> >> They're playing pin the tail on 
the donkey. >> > 
> You could understand what he was saying? I wanted to help but was > 
unsure of what he was asking. I also seem to remember that discussion > 
you are referring too. IIRC, 10,000hz for pooling was the setting they 
 > ere talking about. But on it would very a little, and with the fxp > 
based card polling hurt a little because the card was already ding its 
 > own thing in hardware. So that setting was redundant, it was best to 
 > leave it alone. > He also seemed to say the network bandwidth was 
constant, and system > load rose with an 64bit system. This right? If 
he was using GENERIC on > a smp system he was only using 1 cpu with out 
a recompile. There is > just so much that could be wrong and he gives 
no information on his > system or settings. > Doess he have 2 amd64 pcs 
with 2 different installs of 5.3, or a > single machine that he ran 
both versions on? The router, is that a > third machine that was an 
amd64 system, or something else? He says > i386, but an up to date 5.3 
world doesn't support 386 with out a work > around. The least commom 
setting is now 486, but a build for 686 would > be better. Did he tell 
you if he had polling on? > > So I guess it is a good thing you were 
able to help him, because I > couldn't. Not to mention the flame bait 
you through out, well, that > would be wrong. 
_______________________________________________ > 
> --------- Previous Message 
> 
> No, thats not what I was talking about. They were tuning the MAX_INTS 
> parameter for the em 
> driver, which can hold off interrupts to reduce system overhead. > 
Instead of minimizing the load, 
> they were focused on squeezing a few extra bits out of iperf, which 
is > not how you tune 
> performance. If you get 700Kb/s and have a 95% load and can get > 
695Kb/s with 60% load, 
> which is better? Plus they were testing with a regular PCI bus, so > 
they were hitting the 
> wall on the bus throughput, which changes all the timings, so it was 
> just a stupid test in 
> general. 
 
I would say 60% load. Now I completely understand what you were saying. 
 
> 
> I'm not 100% sure of what he was saying, but I've seen the same 
thing. > I take an i386 disk 
> and pop on an amd64 disk with the same settings, except for the 3 or 
4 > required differences, 
> and the i386 machine has WAY less network load. So maybe your > 
buildworld runs faster, 
> but the whole interrupt/process switching mechanism runs like crap, 
so > you likely have a 
> slower machine. I haven't seen any test that shows otherwise, just a 
> bunch of swell 
> guys swearing that one thing is faster than another. 
> 
> I understand that you don't want to hear the truth, so flame away. 
But > its not going to make 
> things any better. 
 
Ahh! More flame bait! I just didn't like you platitudinal and 
unproductive message that I believe would just drive Boris onto linux 
and leave a possible open problem on FreeBSD for some one else to 
discover latter. It's not that I don't want to hear the truth, you were 
just not saying anything worth his time. But atleast now we can get 
some where to help him and the amd64 port. I also had the idea that 
Boris was just trolling because he has not responded, just said FreeBSD 
was bad and left us to duke it out. 
 
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> 
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