Very Computer

Hi Linux gurus,

What are your opinions on building or buying a
fast machine (> 1.2GHz CPU) with 4GB of main
memories.  SMP is not important at this moment.
RedHat 7.x would be the target operating system.

Regards,

-roger

I recently bought an Asus A7V266-E mother board, with an Athlon XP 1700 cpu
& 256 MB, which works fine.  That mom board supports up to 3 GB of memory.

--

All the facts above are true, except for the ones I made up.

james.knott.

To get 4G or more you will need a server class motherboard. SuperMicro
has a number of motherboards that range from 4G to 16G of memory. Most
desktop motherboards have only 2 or 3 DIMM sockets which limits you to
1.5G at the moment using 512M DDR modules or 3G if you use the
expensive 1G modules (512M is $76 on pricewatch, 1G is $311).

Just out of curiosity, what do you plan to do? We are running two DELL boxex
with dual 1.7 GHZ Xeon's and 1GB RAM.

Thanks for all your responces!

I will be running EDA tools for ASIC designs (mostly
backend).  For certain tasks, a process may take over
3GB of memories.  Another constraint is the turn around
time for this type of applications.  Some jobs take days
to finish, so I don't want the processes to use virtual
memory.  SMP is not that important in my case, since
most tools here do not utilize multiple CPUs.  Besides,
I am concern about the stability of Linux's SMP implementation.

Anyway, I expect to get a 2x performance gain over
SUN machines, and pay less than half of SUN's price
tag.  I am sure there are good Intel-based (or AMD)
boxes out there to provide fast, inexpensive, and reliable
solutions.

Thanks,

-roger

It depends on what you want to do.  For *most* users who
are not standing up web or email servers but, rather,
end-user systems, a machine similar to what you describe
is adequate.  Very few users could justify a dual-cpu
machine on any reasonable price-performance basis, as
very few apps are CPU-bound.  In general, the money
saved in not buying an SMP mobo should be applied to
faster disk and more RAM.  I'd still buy a 1.2 GHz
Athlon today if I could find one, because I just don't
need that much CPU and would rather save the bucks.  Any
CPU that is at least one generation old, however, is a
sweet deal these days.  If you avoid buying the fastest
CPU possible, you'll do fine.  You'll also be more
likely to get complete support for all of your
components if you're not buying on the bleeding edge. My
personal preference is for Asus mobos and video cards
(featuring nVida chips) because of their excellent
manuals, high-quality build process (good registration
of all parts, excellent and readable silk-screening,
good layout, etc.).  If I choose, I can leave my box
running for months without a crash or reboot.  My usual
reason for rebooting is to launch windows to play some
games. (You might consider making a dual-boot machine,
too.  This might tend to increase the amount of disk you
choose to buy.)

It's quite cheap these days to build a machine that
almost never has to page.  That goes a long way toward
making your machine seem very fast.  I run 512MB, and I
can run for days without paging unless I run nautilus
(default in RedHat distros - so find it and kill it and
disable it on your first boot), and or the latest
incarnation of Mozilla, which is very memory hungry.

It sounds to me like you might be best off looking for one of the new Intel
64 bit machines. I believe there are already Linux ports for it - memory
should be pretty much unlimited with the 64 bit os.

Hmm...that could be a problem.  The ia32 architecture is
limited to about 3GB per process, regardless of total system
RAM.  For more than 3GB per process, you'll need a 64-bit
machine (Sun, Alpha, ia64/Itanium, etc.).

Quote:> Another constraint is the turn around
> time for this type of applications.  Some jobs take days
> to finish, so I don't want the processes to use virtual
> memory.  SMP is not that important in my case, since
> most tools here do not utilize multiple CPUs.  Besides,
> I am concern about the stability of Linux's SMP implementation.

> Anyway, I expect to get a 2x performance gain over
> SUN machines, and pay less than half of SUN's price
> tag.  I am sure there are good Intel-based (or AMD)
> boxes out there to provide fast, inexpensive, and reliable
> solutions.

I don't know about AMD solutions supporting 4GB of RAM.
ASUS has some motherboards that support up to 4GB (maybe
more).  SuperMicro's Xeon boards support as much as 16GB of
DDR RAM and dual (P4) Xeon processors.  If you don't
need/want duals, you can still you one of those motherboards
with only one CPU.  Those boards also have nice features
like 64bit/133MHx PCI-X slots for _lots_ of I/O bandwidth.
Or you could always get a dual Xeon, load it with 6-8GB of
RAM, and run two of your compute jobs in parallel.  Just
because your tools don't use multiple CPUs doesn't mean you
can't.  Use more than one app at a time.

If you don't want a build-it-yourself solution with a
SuperMicro motherboard, IBM and Dell offer systems that can
have one or two Xeon processors and gigs of RAM.  (IBM's
Netfinity x235 server or IntelliStation M Pro, Dell's
PowerEdge 2650 server or Precision 340 and 530 workstations,
IIRC.)  Of course, lots of other companies offer similar
products, too.

Note that in Linux on 32bit platforms, a single process is limited
to 3GB of address space.  There is a (reportedly trivial) kernel tweak
out there to make this 3.5GB, but that's all you'll get.

Quote:> time for this type of applications.  Some jobs take days
> to finish, so I don't want the processes to use virtual
> memory.  SMP is not that important in my case, since
> most tools here do not utilize multiple CPUs.  Besides,
> I am concern about the stability of Linux's SMP implementation.

Don't be.  Really.  Linux on 2-4 processors scales quite well and is
heavily tested.  Beyond 4 CPUs it can get dicey, but you won't have
any problems.  And, besides, you're not going to find many (any?) UP
motherboards supporting 4GB of RAM.

Anyways, you're choices are basically dual AMD on Tyan mobos or dual PIII
or Xeon (P4) on Tyan/SuperMicro/Intel mobos.  Dual AMD is going to be
cheaper and just as fast/faster than Intel.  The MPX chipset does
have a limitation, though, where it reserves the top up-to-.5GB of memory
for PCI stuff, meaning that the OS may only see 3.5GB of RAM when you install
4GB.  That's DDR memory, btw.

If you need speed, I'd go with Xeon over PIII for an Intel solution.  You'll
want a board based on the E7500 chipset, which is dual channel DDR.  I've
got a system on a SuperMicro board that I'm quite happy with.

In the end, it comes down to what you're comfortable with.  AMD is going
to be more bang for buck, but *may* be more trouble.  Intel is going to
be pricier, but the server boards tend to be more stable.

Good luck.

--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University

We have a number of boxes on which we installed a kernel patch for 3.5GB
user space.  Search on Google and you will find it. We use them to run
place and route tools on large ASICs and it has helped significantly,
since the alternative is to run on a much slower Sun box. It seems that
many of our jobs use between 3 and 3.5GB of memory.

Quote:

> > time for this type of applications.  Some jobs take days
> > to finish, so I don't want the processes to use virtual
> > memory.  SMP is not that important in my case, since
> > most tools here do not utilize multiple CPUs.  Besides,
> > I am concern about the stability of Linux's SMP implementation.

> Don't be.  Really.  Linux on 2-4 processors scales quite well and is
> heavily tested.  Beyond 4 CPUs it can get dicey, but you won't have
> any problems.  And, besides, you're not going to find many (any?) UP
> motherboards supporting 4GB of RAM.

Our systems are dual-Xeon. They are very stable.

SMP systems are very flexible: some times one might run a single large
job, other times, they can run 2 smaller jobs -- they key is to ensure
that the box has enough memory that it does not do any significant amount
of swapping.

We ran some tests on one of our dual-Xeon boxes, comparing one job on the
machine vs. 2 jobs simultaneously. The total user memory requirement was
kept below the amount of RAM in the machine to eliminate swapping as an
issue.

Our results were:
Single job: ran in 5 hours
2 jobs: one finished after 6 hours, the other after 7.

In other words, I see a SMP machine as equivalent to about 1.5 single
machines. However, one would have to have one machine with 4GB and another
with 2GB to have something comparable. This would cost much more.

Quote:

> Anyways, you're choices are basically dual AMD on Tyan mobos or dual PIII
> or Xeon (P4) on Tyan/SuperMicro/Intel mobos.  Dual AMD is going to be
> cheaper and just as fast/faster than Intel.  The MPX chipset does
> have a limitation, though, where it reserves the top up-to-.5GB of memory
> for PCI stuff, meaning that the OS may only see 3.5GB of RAM when you install
> 4GB.  That's DDR memory, btw.

In our benchmarks, while a dual Athlon MP system gave very similar run
times to the dual-Xeons (1800+ AthlonMP vs. 1.7GHz Xeon with RAMBUS RAM)  
while running our P&R tools, the Dual-Athlon was much slower while running
logic simulation.

Quote:

> If you need speed, I'd go with Xeon over PIII for an Intel solution.  You'll
> want a board based on the E7500 chipset, which is dual channel DDR.  I've
> got a system on a SuperMicro board that I'm quite happy with.

We just got  a new system based on Dual 2.2GHz Xeons on E7500 chipset.
Works well. However, we only installed 4GB. A couple of extra GB might
help it.

Memory bandwidth is likely to be a big issue for performance. The E7500
chipset has a dual-channel memory architecture which should make it better
than an KT333 or other system with only a single memory channel.

Quote:> Thanks for all your responces!

> I will be running EDA tools for ASIC designs (mostly
> backend).  For certain tasks, a process may take over
> 3GB of memories.  Another constraint is the turn around
> time for this type of applications.  Some jobs take days
> to finish, so I don't want the processes to use virtual
> memory.  SMP is not that important in my case, since
> most tools here do not utilize multiple CPUs.  Besides,
> I am concern about the stability of Linux's SMP implementation.

> > > What are your opinions on building or buying a
> > > fast machine (> 1.2GHz CPU) with 4GB of main
> > > memories.  SMP is not important at this moment.
> > > RedHat 7.x would be the target operating system.

If you are installing 4GB of memory, you are wasting your money unless you
install a faster processor. 2.2GHz Xeons or PIVs are very affordable.  
Your saving through buying a 1.2GHz processor(s) will be a couple of
hundred bucks, vs. your memory that is going to cost $1500-$2000.

There is a big jump in price from 2.2GHz to 2.4GHz -- 2.2 seems to be
sweet spot for high performance on a budget. Anything less does not save
enough to be worthwhile for the type of jobs you will be running.

Run Word Perfect 5.1 on DOS 3.  ;-)

--

All the facts above are true, except for the ones I made up.

james.knott.

18.4 exabytes ought to be enough for anybody.  ;-)

--

All the facts above are true, except for the ones I made up.

james.knott.

Quote:> What are your opinions on building or buying a
> fast machine (> 1.2GHz CPU) with 4GB of main
> memories.  SMP is not important at this moment.
> RedHat 7.x would be the target operating system.

   There are motherboards around that will take 4 gigs, just not a
tremendous amount.  One of the best ways as far as performance and economy
is to buy a Tyan Tiger MPX board.  Yes, it's a dual-CPU board, but it's a
little tough to find boards that will take 4 gigs of RAM and *don't* have
more than one CPU.  You can, of course, find motherboards from SuperMicro
and Tyan that will accomodate up to 16 and 24 gigs of RAM, respectively,
but be prepared to pay quite a bit.  If you only need 4 gigs, try the MPX
and a couple of AthlonMP's.  I highly doubt that you'll be disappointed.

  As for the stability of Linux's SMP operation, I wouldn't worry greatly.
It's true that there are still a few drivers floating around that cause
problems in SMP operation, but they're by far an exception, not the rule.
We don't use any servers that *aren't* SMP, and have no problems getting
uptimes in excess of one year.  In fact, the only time any of the machines
have been rebooted in the last 2.5 years was for planned upgrades, or in
one instance, to replace a failed power supply.

steve