The IBM POWER8 Review: Challenging the Intel Xeon
by Johan De Gelas on November 6, 2015 8:00 AM EST- Posted in
- IT Computing
- CPUs
- Enterprise
- Enterprise CPUs
- IBM
- POWER
- POWER8
Trying Out a Different Compiler: IBM's XLC
Based on our previous results the IBM POWER8 has definitely attracted our interest, and we were motivated to test a lot more. Can IBM's own compiler "XLC" boost the scores even more?
To test that out, we joined the IBM OpenPOWER Linux community and downloaded the IBM XLC compiler. We compiled with two different and rather aggressive settings:
- -qhot -O4 -qarch=pwr8
- -qhot -O5 -qarch=pwr8
We've taken our XLC binaries and set them up against binaries compiled with GCC 4.9.2 using the "-o3 -mcpu=power8" flag. The mcpu=power8 flag has very little impact on performance, but we wanted to be sure that GCC was given every opportunity to optimize for the POWER8 CPU.
The results for XLC are very weird. Using the -O4 flag the XLC compiler does pretty badly on compression (-7%), while increasing performance by 7% in decompression. Nothing to write home about. Only when we use the -O5 flag do we get an increase in performance by 7-8%. However we also found that -O5 was too aggressive for most complex software that we ported to the POWER8, and as a result isn't very usable.
We suspect that the XLC compiler for LE Linux is still a bit immature and has still some room to improve. Which unfortunately isn't doing IBM any favors at this moment since XLC is a paid compiler.
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Mondozai - Friday, November 6, 2015 - link
That's too bad. Over 90% of the world population exists outside of it and even if you look at the HPC market, the vast majority of that is, too.The world doesn't revolve around you. Get out of your bubble.
bji - Friday, November 6, 2015 - link
He never claimed the world revolved around him, he just made a true statement that may be worth consideration. Your response is unnecessarily hostile and annoying.I would expand Jtaylor1986's statement: I believe that most if not all native English speaking populations use commas for thousands grouping in numbers. Since this site is written in English, it might be worthwhile to stick to conventions of native English speakers.
It's possible that there are many more non-native English speakers reading this site who would prefer dots instead of commas, but I doubt it. Only the site maintainers would know though.
Jtaylor1986 - Friday, November 6, 2015 - link
You read my mind :)mapesdhs - Tuesday, November 10, 2015 - link
Talking to numerous people around Europe about tech stuff, I can't think of any nation from which someone used the decimal point in their emails instead of a comma in this context. I'd assumed the comma was standard for thousands groupings. So which non-US countries do use the point instead? Anyone know?lmcd - Friday, November 6, 2015 - link
Cool on the rest of the world part, but the period vs comma as delimiters in the world numeric system ARE backward. In language (universal, or nearly), a comma is used to denote a pause or minor break, and a period is used to denote the end of a complete thought or section. Applied to numerics, and you end up with the American way of doing it.^my take
JohanAnandtech - Saturday, November 7, 2015 - link
Just for the record, this was not an attempt to nag the US people. Just the mighty force of habit.ZeDestructor - Saturday, November 7, 2015 - link
For future use: just use a space for thousands seperation (that's how I do it on anything that isn't limited to a 7seg-style display), and confuse readers by mixing commas and periods for decimals :Ptygrus - Sunday, November 8, 2015 - link
I like to use a fullstop for the decimal point, an apostrophe for the thousands separator, a comma for separating items in the list, don't start a sentance with a digit.One list of numbers may be : 3'500'000, 45.08, 12'500.8, 9'500. Second list : 45'000, 15'000, 25'000. We use apostrophes when we contract words like don't so why not use it for contracting numbers where we would otherwise have the words thousand, millions, billions etc ?
mapesdhs - Tuesday, November 10, 2015 - link
I have a headache in my eyeballs! :Dws3 - Friday, November 6, 2015 - link
North America is on the majority side on this issue. Asia, in particular, is almost completely on the side of using a dot as the decimal separator and a comma to put breaks in long numbers.Get with the program Europe. The world doesn't revolve around you!