
Assessing IBM's POWER8, Part 1: A Low Level Look at Little Endian - tambourine_man
http://www.anandtech.com/show/10435/assessing-ibms-power8-part-1
======
superkuh
The best part of POWER8 is the ability to flash and verify the CPU firmware
using a completely open toolchain. All modern Intel and AMD processors have
secret sauce signed firmware (that can even access and use the network). You
can't ever be sure what is running on them internally. POWER8 is a secure
architecture even in the case of an NSA targeted hardware intercept during
shipping. You can just reflash with known/verified good firmware when you get
it.

~~~
jjnoakes
How does this work at the lowest level? How does one know that the flashing
itself is not being subverted or altered by the microcode?

There has to be a level below all of the turtles, right?

~~~
kabdib
You can probably hide evil in a few gates, in the right place. A little
additional logic that perturbs an MMU mapping or TLB load, or fail to register
an exception if a bit of hardware has seen a recent pattern of behavior. Heck,
with a few thousand gates you could have a full microprocessor embedded on the
sly.

I don't know at what point this stuff becomes noticeable; do you subvert the
silicon toolchain? Do you buy off the people who make the masks? Are there
feedback loops in the silicon production chain where changes would make it
back to a designer, who would say "Hmmm, that's funny..."?

In the early 80s it looked possible for a chip designer to stick in Something
Bad without much notice. With billion transistor chips, it seems a lot easier.

Is there a VHDL equivalent of the Underhanded C contest? :-)

~~~
sp332
How about a single capacitor that isn't even connected to anything?
[https://news.ycombinator.com/item?id=11768980](https://news.ycombinator.com/item?id=11768980)

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rdtsc
> Once all threads are active, the IBM POWER8 core is able to outperform the
> Intel CPU by 41% (geomean average).

Nice! I see good multi-threaded performance. Can use regular memory in it as
well. Also someone mentioned already I see but I understand POWER8 doesn't
come with something equivalent to Intel Management (ME) -- the friendly
backdoor inside your server <insert Intel Inside joke here>

~~~
edwintorok
Yes, that is why for the Talos workstation Power8 was chosen:
[https://www.raptorengineering.com/TALOS/prerelease.php](https://www.raptorengineering.com/TALOS/prerelease.php)
[https://www.raptorengineering.com/TALOS/prerelease_specs.php](https://www.raptorengineering.com/TALOS/prerelease_specs.php)

"POWER is the only open, owner-controllable architecture that is competitive
in performance."

If you are interested in using anything other than Intel ME/AMD PSP
"backdoored" desktop, please register your interest, they will only build
Talos if enough people want to order it.

~~~
creshal
I would be interested, but even their minimal configuration is overkill for
me. If there's a 50-70W quadcore option, sign me up.

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Annatar
$4,900 for a barebones system is still too high for a platform meant to
compete with a PC tin bucket server, where 1U barebones start at $800, and a
decent 32GB / 4TB server can be had for $1,800.

Next on the list, if I don't want to run Linux (and I don't) what other
freeware choices do I have? As far as I know only beta versions of AIX were
gratis, everything else had a hefty licensing fee. Those kinds of games don't
fly in this day and age, hence anything that is not intel and freeware and
open source has been relegated to dwindling sales, and close to non-existent
market uptake. itanium, POWER, UltraSPARC - examples aplenty.

When will AIX, the volume manager, and the compilers become freeware / open
source, or at the very least freeware?

~~~
IntelMiner
Do you have any specific preference for what operating system you'd want to
run? Linux seems to be what most people are going to run on it, though the
devices do also run AIX (according to Wikipedia)

Have you looked into the various BSD's to see if they support it (yet?) I used
them a couple years ago on some old Apple PPC hardware I had clunking around
as they ended up running circles around Linux in hardware support and
stability

~~~
Annatar
(Disclaimer: PPC Yellowdog Linux on PlayStation 3 used to be my primary
development system.)

I'd prefer SmartOS, but that only works on intel, as PPC support was removed
from the illumos kernel a long, long time ago. Nevertheless, reverting those
changesets and getting it running again would be cool.

Next on the list, then, would be AIX, an operating system developed on POWER
for POWER.

I also read that FreeBSD has some POWER support, but unlike AIX, it's nowhere
near production quality material yet. FreeBSD would have been my next choice.

------
zmanian
IBM is pushing hyperledger / blockchain on Power8 pretty hard.

Given how much memory bandwidth is a bottleneck on updating the internal
Merkle trees, Power8 might be good for tx throughput

~~~
jacques_chester
IBM are also providing hardware and engineering to get Cloud Foundry running
on POWER8.

I work for Pivotal, we donate the majority of engineering on CF, but IBM is
the next biggest contributor. They've started assigning engineers to work
alongside multiple teams on porting to POWER8 and have started setting up test
clusters as well.

Just this week I was in a remote tri-pairing session with an IBM engineer
working on getting our buildpacks pipelines[0] running on POWER8.

I personally can't wait to see how it performs.

[0] [https://github.com/cloudfoundry/buildpacks-
ci](https://github.com/cloudfoundry/buildpacks-ci)

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rwmj
I'm still waiting for cheap(ish) POWER8 development boards. Any news on that?

~~~
robin_reala
Depends how you define cheapish. Raptor are building a dev board, estimated
price is $3700:
[https://www.raptorengineering.com/TALOS/prerelease.php](https://www.raptorengineering.com/TALOS/prerelease.php)

~~~
rwmj
Somewhere in the $500-1000 range would be cheap enough that I could buy one
and expense it.

~~~
robin_reala
Their estimated price for the board without the CPU is $2700, indicating that
they’re expecting a minimum price for $1000 for the CPU alone.

~~~
rwmj
IBM POWER CPUs are really expensive because their yields must be very small.
However there are other sources of POWER CPUs. POWER CPUs aren't intrinsically
expensive.

Freescale are one (eg. the e5500 - I can't keep up with whether that exact
model was POWER7, but last I checked Freescale did a POWER7 CPU). These are
much cheaper. But the problem with them is they are embedded CPUs (book E?),
so they omit some instructions required to run server versions of Linux. Also
IIRC they are all big endian, or at least had some problem running in LE mode.

Anyway to get to my point: unless there are affordable development boards for
POWER, no one is going to spend much time porting software and fixing bugs for
POWER.

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kartickv
Does POWER have an advantage in price-performance ratio over Intel? When I say
price, it's the TCO, including energy costs.

~~~
rwmj
My take on this is that if you need peak single thread performance and are
willing to pay whatever that costs you should consider POWER. If you are at
all sensitive about price, or if you can expend development effort
parallelizing your work across lower performance cores, you should go with
x86. They are different markets for different people.

I have access to POWER8 hardware through work and it really does scream.
Forget benchmarks, it's noticeable at the command line. Which is nice, but I'm
not paying for it.

~~~
cm3
> Forget benchmarks, it's noticeable at the command line.

What do you mean exactly?

~~~
rwmj
Well I compile libguestfs ([http://libguestfs.org/](http://libguestfs.org/))
on POWER8 fairly regularly and the compilations just fly past. I haven't
benchmarked it, and I'm not allowed to benchmark it because of the NDAs we
sign, but it's obviously faster than the Intel machines we have. Because of
the single-threaded parts of the build (eg. ./configure), these builds benefit
much more than just having lots of cores - Amdahl's law and all that.

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salutte
I would love to see the same benchmark with --march=native. I doubt AVX would
be used without this flag on the Intel platform, and this might be also
hindering the Power8.

~~~
rwmj
FWIW RHEL 7.3 (ppc64le) will be compiled for POWER8 only. As I discovered the
other day, binaries will randomly segfault if you try to run them on POWER7.

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ksec
Assuming they are similar price, POWER8 is roughly 40% better, double the Idle
power, 20% slower Single Thread Performance.

So... why would I want to buy that? I believe at 14nm, Google would likely
make the switch as their scale is different. ( Any % of improvement is a lot
in Google Scale )

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sengork
Summary: it's all about the bandwidth.

