
The IBM POWER8 Review: Challenging the Intel Xeon - msh
http://www.anandtech.com/show/9567/the-power-8-review-challenging-the-intel-xeon-
======
rwmj
I use POWER8 hardware at Red Hat (supplied by IBM[1]) and it certainly does
rock. It helps that I don't have to pay the electricity bills.

I just wish the hardware was more available. There is precisely one, barely
affordable, non-IBM POWER8 system available to buy[2] (if you have $3-4k
burning a hole in your pocket). Where are the development boards?

[1] [http://research.redhat.com/powerlinux-openpower-
development-...](http://research.redhat.com/powerlinux-openpower-development-
hosting/)

[2]
[http://www.tyan.com/campaign/openpower/](http://www.tyan.com/campaign/openpower/)

~~~
Alupis
What are some of the easy benefits of using the POWER series of
processors/architecture?

My company runs an IBM POWER7 series system as our ERP/WMS, but that's really
only because our vendor sold it as part of a package.

From a user standpoint, POWER architecture just means it will cost me more (on
all fronts, from acquisition, to maintenance, to power consumption, etc...).
Come upgrade time, it makes it very unlikely I'll be able to unload this
system on someone else and recoup anything but a few hundred bucks, sold to
someone as a testbench.

When compared to a run-of-the-mill x86 system, POWER doesn't seem to have any
real tangible benefits.

~~~
rwmj
I agree with all your points. The benefit is per-core performance is very very
fast indeed. If you need that, and price is no object, then you should use
POWER.

~~~
kpil
Hmm. Everything we have in our basement is slower than my desktop i7 if you
run exactly one core.

Running all cores at full tilt is another story.

On the other hand,IBM have just tried to book three 3-hour long pitching
sessions with me so it does not sell itself...

------
valarauca1
Benchmarks sound like their fighting hardware frequency throttling more then
actually benchmarking the chips.

One big issue to point out:

>Floating Point: NAMD

GCC sucks at automatic hardware vectorization. So does the LLVM. Really the
only time you can count on getting automatic hardware vectorization is if you
shell out for the ICC __AND __write your code in Fortran. I 'm gonna bet they
didn't vectorized a goddamn thing, but we can't inspect anand's binary so
we'll never know. The results are still _likely_ correct, but IBM should have
lost by a smaller margin.

 __TL;DR __

POWER8 is fun but costs 5k more then Xeon per rack mount and uses about 2x the
power usage for 10% less performance on generalized work loads. But can pull
off 10-15% more performance on _some specialized_ workloads. So meh?

~~~
vonmoltke
My experience has been that icc (the C compiler) does a very good job of auto-
vectorization. xlc does as well, provided you avoid the horribly misdesigned
POWER6 architecture.

I agree that gcc sucks for this; we didn't have LLVM last time I was doing
this kind of work, so I can't comment on that.

~~~
CyberDildonics
If you want to really use SIMD units (on x86) check out ISPC. I recommend
writing small functions in it that work over large chunks of memory so that
SIMD can run at full speed with good cache locality.

This ends up being -very- fast.

~~~
valarauca1
Link for the lazy:
[https://github.com/ispc/ispc/](https://github.com/ispc/ispc/)

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notjustanymike
IBM really needs to hire a professional designer for their slides. That deck
is straight out of a 6th grade science fair.

~~~
tychuz
Did they really used Comic Sans?.. With that yellow discount star sign?..
What. the. hell.

~~~
notjustanymike
It's ok guys. It's just our high-power server CPU architecture. Totally cool
to slap a yellow star sticker with misaligned text on it. I'm not sure if
that's comic sans or a knockoff. Also I just love the teal bevel and big bank
bag of cash. And the stock icons for checkmark, arrow, and question mark. And
the complete and total misalignment of all the text.

Goodness grief.

~~~
antod
No No No - you are totally missing the point.

The design language used in those slides has been iteratively refined over
decades and exhaustively A/B tested. It has many years of psychometric
analysis applied to make it one of the most powerful sales tools in the world.

To win over enterprise PHBs, you need to make them think that you are one of
them. That you understand and empathise with them deeply. That you speak their
language, and that you are part of their culture.

What better way to do that than to give them a powerpoint presentation that
looks just like the ones they give each other. That shows that you are already
part of their world, and that you are worthy of the key to the executive
washroom.

------
chkuendig
single-page link: [http://www.anandtech.com/print/9567/the-power-8-review-
chall...](http://www.anandtech.com/print/9567/the-power-8-review-challenging-
the-intel-xeon-)

------
Quequau
I'd be a lot more excited about this if they were more accessible. I can
barely justify an upgrade to whitebox Intel Xeon servers and there's just no
way I could rationalize the prices that IBM demands.

------
RexRollman
POWER, OS/2, and The Thinkpad has convinced me that IBM just doesn't make the
most of what they create.

~~~
rdtsc
> POWER, OS/2, and The Thinkpad has convinced me that IBM just doesn't make
> the most of what they create.

They are all kind of different.

I used to use Thinkpads and I hated IBM for selling it. But from their point
of view it was the absolute right thing to do. High end consumer laptops are
dominated by Apple (heck IBM is buying Apple and giving them to all their
workers, something like 300K Mac Book Pro's). Everything else is racing to the
bottom with thinner and thinner margins. Windows running laptops have to
compete with Asus and friends and the money just wasn't there.

Not sure about OS/2 much, don't remember the history. But with POWER, IBM has
kind of started to turn around in the last few years.

At some point in the past they have made an explicit choice to not play in the
consumer market. Heck, there used to be IBM stores, you'd walk in and buy IBM
products like you go to an Apple store now. But they decided they don't want
to play in that market (or better or for worse). We'll still see how it ends
up working out.

So far it still stays in business after hundreds of years, maybe it just luck
or there is something to its business approach. (Fun fact, it used to sell
cheese slicers and time tracking devices as well at some point).

~~~
epc
OS/2: decent OS, ahead of Windows for awhile, but IBM was never going to go to
the mattresses enough to get it the install base it would need to compete with
Windows. IBM's dysfunctional PC division didn't help. It would have been nice
if IBM kept OS/2 up as a specialty operating system, but I think the overhead
costs were too much and Gerstner was, by 1996-1997, very much in a kill-
anything-that-isn't profitable mode.

Prior to Gerstner, IBM had a variety of esoteric products which were solely
designed as loss leaders, never earned a profit, and relied on subsidies by
other parts of the company to stay alive. Post 1993, really starting in
1994-1995 these got killed off or sold off, rapidly.

It wasn't enough to break even, one number I recall being thrown around was
that we had to get to a 12% Expense-to-Revenue ratio, ignoring SG&A which was
a corporate-wide number. Growth products, products in new markets were
exempted entirely or given better targets, but old-line products were held to
this magical 12% ratio (I was in the mainframe division at the time, which was
grotesquely profitable and even today subsidizes much of the rest of IBM).

~~~
rdtsc
Interesting stuff. Thanks for explaining.

I was surprised that IBM even had physical stores at some point and today
average consumer probably has absolutely no idea what IBM does.

~~~
epc
I don't think the physical stores lasted long, they eventually were sold off
to ComputerLand, possibly as part of a consent decree (before my time). A lot
of bad business decisions at IBM start with the various consent decrees it
operated under as a result of various antitrust cases, and the utter fear of
yet another antitrust case developing.

~~~
rdtsc
Yeah it didn't seem like they were really big and would have lasted, but it
was kind of a contrast with today where a young person on the street would
probably have not idea what IBM does.

~~~
scholia
IBM was big, really big. At one time, it had more than 70% of the computer
business, so it was twice as big as every other computer company added
together.

In fact, IBM was really big before computers even arrived. It dominated data
processing based on punch cards and was sued for monopoly abuse in the 1930s.
It was the original Evil Empire.

Microsoft -- founded in 1975 -- has been spectacularly successful, and IBM's
performance has been mediocre for the past 15 years. Even so, Microsoft has
only just overtaken IBM in revenues. (Both are now around $93 billion. On any
reasonable growth path, IBM would be well over $200 billion.)

See the graph at [http://www.zdnet.com/article/tiny-microsoft-overtakes-the-
mi...](http://www.zdnet.com/article/tiny-microsoft-overtakes-the-mighty-ibm/)

Indeed, Microsoft would probably be nowhere without IBM. It was IBM that set
the PC standard with the IBM Personal Computer in 1981, and Microsoft was
lucky to be part of it. In IBM terms, Microsoft stole a small part of IBM's
rightful monopoly. IBM's response was to try to kill it with OS/2 EE and the
MCA bus in PS/2 computers, as part of SAA.

------
scythe
I've wondered something: MIPS and ARM have both made inroads in the low-power
market, supposedly because RISC supports power-efficiency (x86 microcodes
notwithstanding), but POWER has always been described as less power-efficient
than x86 or other architectures. What makes POWER need so much... uh, power?

~~~
aidenn0
At the high-end, the power-costs of ISA are negligible. Even at laptop levels
of power consumption it's barely noticeable. Once an Intel chip has decoded
the instructions to uOps, it is mostly on an even playing-field with RISC
chips.

Also, to be pedantic, POWER is very much not RISC; the only thing it really
has in common with RISC is fixed-length instruction encoding (though simpler
instruction decoding is an advantage at really low powers).

~~~
scythe
>At the high-end, the power-costs of ISA are negligible. Even at laptop levels
of power consumption it's barely noticeable. Once an Intel chip has decoded
the instructions to uOps, it is mostly on an even playing-field with RISC
chips.

This doesn't actually answer my question at all, it's just a canned response
to something I alluded to in my question (CISC vs. RISC) and a debate which I
don't fully understand and would rather avoid. The question was _why does
POWER consume so much power_ , not _why doesn 't POWER being RISC matter_? The
only reason I compared it to MIPS and ARM was that I thought it was similar to
those architectures and they're considered to be low-power.

The impetus is that POWER is actually _worse_ than other architectures,
_including_ x86, for unexplained reasons, w.r.t. power consumption.

~~~
aidenn0
POWER consumes more power because IBM has not optimized for that to the degree
that Intel has. The PA6T was _extremely_ power efficient (and was designed by
a team headed by the same person who designed StrongARM (became X-scale) and
SiByte's (now purchaesed by Broadcom) MIPS chips).

[edit]

To clarify, the difference between ISAs for power efficiency is negligible at
all but the lowest powers, which is what I was trying to say in my original
response. The Pentium 4 was far less power efficient than the contemporary G4
PowerPC, as a counterexample. If the power difference between two chips is
more than 1 watt per instruction decode unit, you can probably safely assume
it's not due to the ISA.

------
1amzave
Why are they using MIPS as a metric for comparing integer CPU performance?
When you're looking at two different compiler backends targeting two (very)
different ISAs, it seems pretty thoroughly uninformative.

~~~
blt
In benchmarks MIPS usually means "we arbitrarily say that reference machine X
runs this benchmark at Y MIPS". Then, for a different machine Z, Z_MIPS = Y *
(X_TIME / Z_TIME).

For example, the 7zip benchmark used in this article is "normalized with
results of Intel Core 2 CPU" [1], or the famous Dhrystone integer benchmark's
"VAX MIPS" [2].

Still I agree it's weird terminology. It would make more sense to use the true
units of the benchmark, or just say "performance relative to reference
machine".

[1] [http://www.7-cpu.com/](http://www.7-cpu.com/)

[2]
[https://en.wikipedia.org/wiki/Dhrystone](https://en.wikipedia.org/wiki/Dhrystone)

------
AnthonyMouse
POWER/PowerPC is the same architecture that Apple once used in the Macintosh,
so if you want to play with Linux on a PowerPC machine they can be had for
almost nothing on the used market.

There are really only two models worth having, at opposite ends of the
spectrum: The PowerMac G5 (64-bit, based on POWER4) was the fastest available
but they're enormous and power hungry. At the other end, the G4 mini is much
smaller and more efficient but 32-bit and not as fast.

~~~
justincormack
32 bit is not worth having, nothing modern supports it.

The G5 was supported with Fedora until recently but alas support was dropped.
Also the newer Power distros are the new ppc64le flavour, which is a slightly
different ABI and little endian but the G5 is not alas dual endian so does not
support it. But they are cheap and quiet and mine has been running reliably,
although I might install FreeBSD on it next as that has ongoing support.

~~~
josh64
I have a 2.3GHz dual core PowerMac11,2 running FreeBSD 10.2 PPC64 on a ZFS
root. My machine has 8GB of RAM and works brilliantly.

I tried all flavours of PPC linux and none of them worked particularly well.
FreeBSD 10.x had the advantage of 64 bit support and the nvidia 6600LE works
acceptably with the open source drivers.

I highly recommend FreeBSD 10.x PPC64 to anyone with a G5 PowerMac who wants
to run a modern OS.

------
apaprocki
Now if only they ran the same benchmarks on a 64-core 4.3ghz POWER8... If your
workload scales better on larger boxes, it can be pretty attractive.

~~~
power8scale
Nobody's workload scales better on bigger core boxes without some serious
attention to contention and lock avoidance.

------
transfire
Damn IBM, just cut your price in half (including those CDIMMs), and destroy
these Xeon monkeys. Why are you being so coy?

~~~
twoodfin
I don't think IBM wants customers that would buy Power 8 were it not for the
price premium over roughly equivalent Xeons. The customers they want will be
writing much, much larger checks for services and support.

