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Benchmarks for Linux Applications on S/390 Zseries?
qaseem asks: "I am looking for benchmark results of various
applications (DB, WebAS, mail, etc.) on Linux on the S/390 mainframe.
I am also looking for tools to stress test these applications when
installed in the S/390 Linux partition. I was wondering if anyone has
seen such information or tried such tools. On a side note I am also
interested in finding a way to relate the MIPS speed of the S/390 to
the world of MHz or GHz on other platforms."
Do you want benchmarks of different products on the same platform, or the same product on different platforms?
Yeah, right.
I searched Red Books just using the keyword Linux, and got the following list. S/390 is the old name for the zSeries eserver, so take a look at Linux for IBM e-server zSeries and S/390: Distributions.
You won't learn too much when you compare MHz to MIPS with an S/390. They are fairly slow, but they do have a TON of memory bandwidth and very fast RAM. At my school we still do mainframe asm programming, and it was pretty clear that machine could move memory like crazy.
DB apps and the like should run nice and fast... makes sense... that is the reason S/390's still exist.
Mainframes have the largest (fastest) CPUs except for the class of supercomputers.
Benchmarking a mainframe involves standalone use, which is rarely accessible except when performing a benchmark. It is analogous to single user operation on Linux. You cannot obtain a performance measurement in a multiuser environment. It's like trying to get Quake FPS numbers while there are 200 other users logged into your Linux machine, doing who knows what. You'd be lucky to get two measurements the same, and neither would be valid.
The mainframe instruction set also contains incredibly complex instructions, which are microcoded. The SIE (start interpretive execution) instruction is an example. This single instruction handles the execution of a virtual machine in it's own unique environment (this is what handles running multiple Linux virtual machines on the same mainframe). This makes the concept of "MIPS" and "MHz" completely meaningless.
As a result, benchmarks concentrate on throughput: transactions per seconds or workload executions per unit time.
Someone else mentioned the I/O system on mainframes. The architecture is somewhat analogous to using a PostScript printer, from the 22,000 mile view. The CPU writes a program (channel program; a collection of CCWs -- channel command words). It transfers that to one of the, possibly multiple, dedicated I/O CPUs called IOPs (I/O Processors) in the mainframe with a single instruction. These IOPs in turn transfer operations to the dozens to hundreds of device controllers (over 1-16 of the possibly hundreds of parallel ~OC3 speed I/O channels), which are small I/O computers outside the mainframe. The controllers in turn talk to the actual devices (up to 32 per controller). There can be (and frequently are) thousands of devices attached to the mainframe at once (disk drives, communications controllers, printers, tape drives, etc.).
All I/O operations are asynchronous and essentially DMA. Much of the I/O error recovery is performed by the IOP and controllers without intervention from the main CPUs. In addition, misbehaving devices can be identified and recovered independantly, or isolated from the system. There's no such thing (barring a now very rare bug) as a malfunctioning device causing a system failure.
Memory bandwidth is very high as has been mentioned, but it's also multiported, multiplying the bandwidth. That is, memory is read and written to concurrently by multiple CPUs and IOPs.
The ideal mainframe environment is one in which the CPUs are running at about 80-85% average CPU utilization, 7x24x365. Enough headroom for peaks, but well utilized. The elimination of all bottlenecks in the processing complex is a required requisite to achieve this state. It's the ultimate hardware hacker/overclockers dream machine.
Can You Say Linux? I Knew That You Could.
I need benchmarks for different products on the same platform. Thanks.
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Everyone knows that mainframes can be mighty fast when running OS/390 apps... the better question would be, how well does the zSeries Linux take advantage of IOPs and stuff like that... If it does, it should fly - if it doesnt, then you're probably better of running DB2 or something on the mainframe and have a couple of intel based linux boxes in front doing the rest of the work (webservers, ...) DOes anyone know if Linux on the zSeries takes advantages of the mainframe architecture?