AMD64 much slower than i386 on FreeBSD 5.4-pre
hardcodeharry at yahoo.com
Thu Mar 24 09:20:12 PST 2005
--- jason henson <jason at ec.rr.com> wrote:
> em1897 at aol.com wrote:
> >> The answer, Boris, is that the "team" has no idea
> >> 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
> >> 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
> > 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.
> > _______________________________________________
> > freebsd-questions at freebsd.org mailing list
> > To unsubscribe, send any mail to
> > "freebsd-questions-unsubscribe at freebsd.org"
> 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:
I always use
systat -vmstat 1
to monitor usage. I also know to set MAX_INTS
in if_em.c file. I use 8000 for both tests.
I try with broadcom NICs soon.
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