# Thread: AMD FX-8350 Linux Performance-Per-Watt

1. Phoronix Member
Join Date
Sep 2007
Posts
80
Meh, is there anything I calculated correctly?

2. Senior Member
Join Date
Sep 2007
Posts
240
@Michael:
Reading the article, every test result my brain stretched and wondered what was wrong. Yet, as mcgreg already said, the only really valid number to compare the processors' efficiency is to calculate the energy which is needed to get the job done. And this, Michael, should be sone by calculating the integral of your W(t) curves... As you have discrete measurements with a fixed step size in time, dt, it's nothing more than a sum over all measurements, multiplied by dt.

dt * \sum_{i=0}^{N} W_i

If you know how many floating point operations this task needs, you can calculate the energy per floating point operation -- which is the same as the average number of Watts per Speed (measured in flop / sec).

3. Senior Member
Join Date
Feb 2008
Location
Linuxland
Posts
4,733
Hm, right. There's still the discrepancy of the idle and load numbers though (at stock), in Win reviews 8350 was lower in both, here the other way around.

4. Senior Member
Join Date
Dec 2009
Posts
492
Originally Posted by curaga
Hm, right. There's still the discrepancy of the idle and load numbers though (at stock), in Win reviews 8350 was lower in both, here the other way around.
Would it be the first time power saving on Linux didn't work right?

5. Senior Member
Join Date
Feb 2008
Location
Linuxland
Posts
4,733
Originally Posted by bug77
Would it be the first time power saving on Linux didn't work right?
It could just as well be 8150 power-saving not working well on Windows. Don't jump to conclusions.

6. Junior Member
Join Date
Jul 2009
Posts
9
I'm sorry but the performance per watt graphs are wrong, that is assuming the power consumption graphs are correct, for example in the C-Ray test the blue line is both higher and longer than the green line, so the system in blue (AMD FX-8150 @ 4.00 Ghz) took more power at each moment in time and also took more time to complete the test than the system in green (AMD FX-8350) - yet the performance per watt says that more is better and green is lower than blue (which from the other graph should green should have more) ... so either less is better in the performance per watt graphs or the formula used for the calculation is wrong.

Numbers
- green took 31.45 seconds @ 220 Watts
- blue took 33.03 seconds @ 262 Watts
So in performance per watt, green is the obvious winner - less time to finish, less average power.
Last edited by xception; 10-28-2012 at 06:33 AM.

7. Senior Member
Join Date
Jan 2010
Location
Portugal
Posts
944
Originally Posted by xception
I'm sorry but the performance per watt graphs are wrong
No need to apologize, since you are correct as most of the posts in this thread confirm. The one who should be giving an explanation is Michael, but I don't even know if he realizes the formulas he used to calculate performance per watt are wrong.

Originally Posted by xception
Numbers
- green took 31.45 seconds @ 220 Watts
- blue took 33.03 seconds @ 262 Watts
So in performance per watt, green is the obvious winner - less time to finish, less average power.
That's pretty obvious. It's not like Phoronix has a ton of credibility anyway so no real harm done.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•