POWER7 Spec

By: Linus Torvalds (torvalds.delete@this.linux-foundation.org), February 10, 2010 1:25 pm
Room: Moderated Discussions
Michael S (already5chosen@yahoo.com) on 2/10/10 wrote:
>
>Core2-4M gets somewhat lower work-per-cycle than Itanium.

Yeah, you need the 6M L2 cache to get better numbers, I
think. I picked various random SpecInt cases, I didn't
really check more than a couple.

>When normalized to CPU cycles the Core2 FSB frequencies
>are lower, much lower. Don't forget that Core2 has 64-bit
>quad-pumped FSB vs Itanium's 128-bit double-pumped FSB.

I did indeed miss that, and only looked at the 1066/1333Mhz
vs 667MHz thing, without checking how wide the interface
was.

But that just strengthens my argument: the Itanium
memory system is sure as hell not slower (when doing the
"normalized-to-cpu-clock" comparison)

But yeah:

>That doesn't follow. Itanium FSB is faster but MCH is
>somewhat slower and memory itself is significantly slower.
>I'd guess random access on rx2660 is in 85ns range
>vs 55-to-60 ns on desktop C2D. So, per clock, Itanium is
>25-30% faster rather than twice faster.

Yeah. That FBD overhead is noticeable. Itanium still
ends up with an advantage, but it ends up being much less
than 2x.

>The best Xeon-3333/FBD 403.gcc score is 21.9/16.9
>403.gcc most definitely doesn't like FBDIMMs.

One of the reasons gcc is such a great benchmark is that
it's all about pointers. FBD has bad latency, and then
when you match that up with a high frequency CPU it gets
worse.

>I disagree. If that was the case low-clocked FBD-based
>Xeons would have higher scores than Itanium. It doesn't
>happen.
>
>The best Xeon-1867/FBD 403.gcc score =13.7/11.2 i.e. ~5%
>lower per clock than the best of Itanium.

There's a Dell that gets 14.1/11.2, which is pretty much
the same as Itanium clock-for-clock (2% difference if I
did the math correctly):

http://www.spec.org/cpu2006/results/res2008q4/cpu2006-20081013-05643.html

That's 1866/FBD too.

Linus
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
POWER7 SpecParadox2010/02/08 11:05 AM
  POWER7 SpecThu Nguyen2010/02/08 12:58 PM
    POWER7 SpecIan Ameline2010/02/08 09:22 PM
      POWER7 SpecThu Nguyen2010/02/08 11:54 PM
        POWER7 SpecIan Ameline2010/02/09 06:46 AM
          POWER7 SpecLinus Torvalds2010/02/09 07:57 AM
            industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 08:09 AM
              industry-standard single-threaded performance benchmarks absentParadox2010/02/09 08:33 AM
                industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 09:30 AM
                  industry-standard single-threaded performance benchmarks absentParadox2010/02/09 10:52 AM
                    industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 11:33 AM
              industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 08:48 AM
                industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 09:26 AM
                  industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 09:58 AM
                    industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 12:17 PM
                      industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 12:54 PM
                        industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 02:10 PM
                    industry-standard single-threaded performance benchmarks absentParadox2010/02/09 01:22 PM
                industry-standard single-threaded performance benchmarks absentanon2010/02/09 10:21 AM
            POWER7 SpecJesper Frimann2010/02/09 12:30 PM
            POWER7 SpecDoug Siebert2010/02/09 05:38 PM
              POWER7 SpecLinus Torvalds2010/02/09 07:28 PM
                POWER7 SpecLinus Torvalds2010/02/09 07:28 PM
                  POWER7 SpecIan Ameline2010/02/09 08:02 PM
                    POWER7 SpecDoug Siebert2010/02/09 10:18 PM
                POWER7 Specsomeone2010/02/09 08:20 PM
                  POWER7 SpecLinus Torvalds2010/02/10 09:17 AM
                    POWER7 SpecLinus Torvalds2010/02/10 09:46 AM
                      POWER7 SpecEmil2010/02/10 11:06 AM
                    POWER7 SpecIan Ameline2010/02/10 10:13 AM
                    POWER7 Specsomeone2010/02/10 11:01 AM
                      POWER7 SpecLinus Torvalds2010/02/10 11:32 AM
                        POWER7 SpecMichael S2010/02/10 12:30 PM
                          POWER7 SpecLinus Torvalds2010/02/10 01:25 PM
                            POWER7 Specmpx2010/02/10 02:58 PM
                        POWER7 Specnemlis2010/02/11 12:24 AM
                          POWER7 Specnone2010/02/11 12:52 AM
                            POWER7 Specnemlis2010/02/11 01:52 PM
          POWER7 Specmpx2010/02/09 08:18 AM
          POWER7 SpecMichael S2010/02/09 09:08 AM
        POWER7 SpecJesper Frimann2010/02/16 02:29 AM
          POWER7 SpecJamie Lucier2010/02/16 06:35 AM
            POWER7 Specanon2010/02/16 07:16 AM
              POWER7 SpecJamie Lucier2010/02/16 10:46 AM
                POWER7 Specanon2010/02/16 03:42 PM
                  POWER7 SpecJamie Lucier2010/02/18 06:07 AM
              POWER7 SpecThu Nguyen2010/02/16 01:23 PM
            POWER7 SpecParadox2010/02/16 09:57 AM
              POWER7 SpecJamie Lucier2010/02/16 11:22 AM
                POWER7 SpecParadox2010/02/16 02:00 PM
            POWER7 SpecJesper Frimann2010/02/16 02:14 PM
              POWER7 SpecJamie Lucier2010/02/17 10:41 AM
  POWER7 SpecJesper Frimann2010/02/09 04:43 AM
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