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New SPECweb99 Benchmarks Shows The Scalability of Linux

Sep 05, 2000, 06:51 (7 Talkback[s])
(Other stories by Marty Pitts)

By Marty Pitts, Linux Today

In early July there was a lot of excitement about the SPECweb99 results of two almost identical Dell machines, one running Tux 1.0 on Red Hat Linux and the other running Internet Information Server 5.0 on Windows 2000. The results showed the Linux machine with over 2.5 times the performance of the Windows 2000 machine.

Linux Today reader, Anthony Awtrey, noticed that recently another Dell machine has been added to the SPECweb99 results page. Interestingly enough, this machine has 8 processors.

Previous stories have focused on the comparision between the results of Linux and Windows machines with 4 processors each. The spotlight this round highlights the the scalability of Linux and Tux 1.0 (a new Red Hat product) over 1, 2, 4 and 8 processors.

The Machines

  • The single processor machine is a PowerEdge 2400/667, running a 667MHz Pentium IIIEB processor with 2GB of RAM, 256KB of secondary cache and 1 network controller, and had 6 Windows 2000 clients over a gigabit ethernet network requesting connections. It scored 1270 on the SPECweb99 Benchmark.
    Full disclosure page
  • The dual processor machine is a PowerEdge 4400/800, running 2 800MHz Pentium III Xeon processors with 4GB of RAM, 256KB of secondary cache and 2 network controllers, it had 12 Windows 2000 clients over a gigabit ethernet network requesting connections. It scored 2200 on the SPECweb99 Benchmark.
    Full disclosure page
  • The quad processor machine is a PowerEdge 6400/700, running 4 700MHz Pentium III Xeon processors with 8GB of RAM, 2MB of secondary cache and 4 network controllers, it had 20 Windows 2000 clients over a gigabit ethernet network requesting connections. It scored 4200 on the SPECweb99 Benchmark.
    Full disclosure page
  • The eight processor machine is a PowerEdge 8450/700, running 8 700MHz Pentium III Xeon processors with 32GB of RAM, 2MB of secondary cache and 8 network controllers, it had 40 Windows 2000 clients over a gigabit ethernet network requesting connections. It scored 6387 on the SPECweb99 Bechmark.
    Full disclosure page

All of the client machines used were Dell Precision 410 workstations with duel 450 Pentium II processors, 128MB of RAM and were running Windows 2000 Professional.

Some simple math shows the increase in performance as Tux 1.0 scales across processors. We see:

A 73.23% increase from a single proccessor system to a dual system,
a 90.91% increase from a dual system to a quad system,
and a 52.07% increase from a quad system to a 8 processor system.

You will notice on the disclosure pages the changes in hardware from one machine to the next. This reflects what happens in the real world. You would hardly order a single processor server to the same hardware specifications as you would an eight processor machine. The biggest changes show up in the different between the 2 and 4 processor servers. It should also be noted that beyond 4 CPUs, scaling becomes more difficult as the Intel bus architecture only supports 4 CPUs per bus.

Moving to the Intel Xeon processors gives a hefty boost to the performance when comparing a single CPU to a dual CPU machine. The greatest jump in performance shows up in moving from a dual CPU machine to a Quad CPU system. This seems contrary to what you would expect, since the Quad system runs 700MHz Xeon processors, instead of at 800MHz that the Dual CPU system uses. A source close to the testing of the machines indicated that the difference in Secondary Cache, 2MB as opposed to 256KB is the 'critical differentiator'.

I was able to contact a source who has knowledge about the hardware used and the tests performed. He commented on the differences in the hardware used:

"The scaling that is shown by the Dell results is somewhat inflated in the 1-2 and 2-4 comparisons due to the changes in hardware. If you look closely, you see that the 1 CPU result used a 667MHz PIII, while the 2 CPU result used 2 800MHz Xeons, plus twice as much memory, and a more powerful memory subsystem. Then, going from 2-4 processors, we went from 800MHz Xeons to 700 MHz Xeons, which again is a step up in per-CPU power (even though it doesn't appear that way) because the cache size went from 256K to 2MB."

What is TUX?

In a previous article Ingo Molnar, the author of TUX, said:

Tux is:
  • an event-based HTTP protocol stack providing encapsulated HTTP services to user-space code
  • object cache, where objects can be combined with dynamic content freely. You can witness this in the SPECweb99 submission, the SPECweb99 TUX dynamic module (every vendor has to write a SPECweb99 module to serve dynamic content) 'embedds' TUX objects in dynamic replies. The TUX object cache is not a dumb in-memory HTTP-reply cache, it's a complex object cache providing async disk IO capabilities to user-space as well. User-space application code can request objects from the cache and can use them in dynamic (or static) replies.
  • full fledged webserver providing HTTP 1.1 keepalive, CGI, logging, transparent redirection, and many other features.

So in our opinion TUX is a new and unique class of webserver, there is no prior art implementing such kind of 'HTTP stack' and 'abstract object cache' approach. It's, I believe, a completely new approach to webserving.

TUX 1.0 takes advantage of new features the 2.4 kernel including the new Linux TCP/IP architecture, VFS cleanups and scalability improvements, the per-CPU SLAB cache, the I/O scheduler and large file support.

So when will TUX 1.0 be available? According to the 'SPECweb99 Run and Reporting Rules General Availability Dates':

All the system, hardware and software features are required to be generally available on or before date of publication, or within 3 months of the date of publication.

As it turns out, Ingo Molnar has released alpha source code on September 1st, (see related stories), with the 1.0 consumer release due out by the end of September.

Ingo Molnar said in a previous interview (see related stories) that the code will be released under the GPL. TUX will be distributed via RPMs and Source Code. Since TUX is kernel-subsystem, it will be vendor-neutral.

Benchmarks should not be your only consideration for hardware and software decisions. Remember Mindcraft? These results, from a company that sells both Windows 2000 and Linux machines, are an indication of the bright future Linux has in the Enterprise. With the coming release of the 2.4 Kernel, Linux has the advantage over proprietary software.

For the average user, having a system capable of such SMP performance may not seem to be much of an advantage. Most of us don't have the need for a 4 or 8 CPU system. But with the increase in scalability soon to be available, one more excuse not to use Linux in the Enterprise will be invalid. Increased use in the Enterprise means more applications and a larger mind share.

For a certainty, we are entering the halcyon days of Linux.

Here more information on the SPECweb99 Benchmark.

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