New Silicon Insider Article

Article: Escape From the Planet of x86
By: Bill Todd (billtodd.delete@this.metrocast.net), June 19, 2003 7:53 pm
Room: Moderated Discussions
Paul DeMone (pdemone@igs.net) on 6/19/03 wrote:
---------------------------
>Bill Todd (billtodd@metrocast.net) on 6/19/03 wrote:
>---------------------------
>
>>One more interesting tidbit that I noticed in that presentation was the L3 latency
>>of 14 clock cycles. My recollection is that McKinley's L3 latency was 12 cycles
>>(though it may have been more in some situations - ISTR the range 12 - 15 cycles
>>being mentioned once): does this indicate a slightly sub-linear improvement in
>>L3 performance for Madison?
>
>I found an old spreadsheet in which I modeled the Merced and McKInley cache
>and memory hierarchies. The representative figure for average memory access
>for a SPECint style workload for a 1 GHz McKinley was 2.34 cycles.
>
>If you simply increase clock rate to 1.5 GHz this figure increases to 2.82 cycles.
>Increasing L3 latency from 12 to 14 cycles increases this to 2.84 cycles. Now
>if you reduce the L3 global miss rate by 29% to account for the capacity doubling
>to 6 MB using the inverse square root rule of thumb then average memory latency
>falls back to 2.42, a bit more than the McKinley figure we started with. Extending
>that to the reported Madison+ (1.8 GHz, 9 MB) and the latency falls to 2.40 cycles.
>And if the Madison+'s 9 MB L3 latency goes up another 2 cycles, to 16, we stay
>at 2.42 cycles. All in all a remarkably scalable memory hierarchy that preserves
>the system level infrastructure (a 1.8 GHz Madison+ will generate roughly the
>same level of memory traffic as a 1 GHz McKinley yet yield perhaps 70% or
>more higher performance on most CPU intensive workloads).
>
>The specific numbers will vary from code to code of course but I think it is clear
>that the increase in L3 latency is completely negligible compared to CPU clock/
>memory access time scaling mismatch. And that in turn isn't a big issue since
>another analysis I did based on published I2 CPI breakdown data for SPEC CPU
>2k suggested McKinley's performance scaling factors were calculated at above
>90% for both SPECInt and SPECfp and actually improved for Madison despite its
>higher clock rate.

So if I managed to get past all that gushing appreciation to the heart of the matter, it sounds as if your analysis predicts a SPECint_base score for the 1.5 GHz Madison of something like 1175 (assuming unchanged compiler technology). I just keep thinking back to Arcadian's glowing assurances that Madison would beat the bejazus out of Opteron and wondering if it can really be that low.

- bill

< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
New Silicon Insider ArticleDavid Kanter2003/06/17 02:39 PM
  Srockholm Syndromeanonymous2003/06/17 02:50 PM
    Srockholm SyndromeNate Begeman2003/06/17 03:32 PM
      Srockholm Syndromeanonymous2003/06/18 01:23 PM
      Srockholm SyndromeScott Robinson2003/06/20 07:25 AM
  New Silicon Insider ArticleBill Todd2003/06/17 08:51 PM
    New Silicon Insider ArticleAlberto2003/06/18 06:29 AM
      New Silicon Insider ArticleJosé Javier Zarate2003/06/18 09:16 AM
      New Silicon Insider ArticleBill Todd2003/06/18 02:10 PM
        New Silicon Insider ArticleNate Begeman2003/06/18 02:25 PM
          New Silicon Insider ArticleTvar'2003/06/18 02:41 PM
            New Silicon Insider ArticleAlberto2003/06/18 02:58 PM
              New Silicon Insider ArticleTvar'2003/06/18 03:04 PM
                New Silicon Insider ArticleAlberto2003/06/18 03:24 PM
                  New Silicon Insider ArticleTvar'2003/06/18 03:32 PM
            New Silicon Insider ArticlePaul DeMone2003/06/18 03:13 PM
              New Silicon Insider ArticleTvar'2003/06/18 03:23 PM
          New Silicon Insider Articlemas2003/06/18 03:11 PM
        New Silicon Insider ArticleAlberto2003/06/18 02:45 PM
          New Silicon Insider ArticleBill Todd2003/06/18 10:46 PM
            New Silicon Insider ArticleDavid Wang2003/06/18 11:13 PM
              New Silicon Insider ArticleBill Todd2003/06/19 12:14 AM
              New Silicon Insider ArticleDavid Wang2003/06/19 09:52 AM
        New Silicon Insider ArticlePaul DeMone2003/06/18 03:04 PM
          New Silicon Insider ArticleBill Todd2003/06/18 10:28 PM
            New Silicon Insider ArticlePaul DeMone2003/06/18 11:43 PM
              New Silicon Insider ArticleRob Young2003/06/19 09:23 AM
                New Silicon Insider ArticleBill Todd2003/06/19 03:53 PM
      New Silicon Insider ArticleDavid Wang2003/06/18 10:29 PM
      New Silicon Insider ArticleBill Todd2003/06/18 11:03 PM
        New Silicon Insider ArticleJosé Javier Zarate2003/06/19 04:33 AM
        New Silicon Insider Articlemas2003/06/19 05:37 AM
          New Silicon Insider ArticleBill Todd2003/06/19 03:40 PM
            New Silicon Insider ArticleDavid Wang2003/06/19 04:25 PM
              New Silicon Insider ArticleBill Todd2003/06/19 05:00 PM
                New Silicon Insider ArticleAlberto2003/06/19 05:29 PM
                  New Silicon Insider ArticleSpeedy2003/06/19 05:48 PM
                    New Silicon Insider ArticleAlberto2003/06/20 03:57 AM
                New Silicon Insider ArticleDavid Wang2003/06/19 05:52 PM
                  New Silicon Insider ArticleBill Todd2003/06/19 08:00 PM
                    New Silicon Insider ArticleAnonymous2003/06/20 01:20 AM
                      New Silicon Insider ArticlePaul DeMone2003/06/20 08:11 AM
                        New Silicon Insider ArticleAnonymous2003/06/22 03:48 PM
                          New Silicon Insider ArticlePaul DeMone2003/06/22 04:49 PM
                            New Silicon Insider ArticleVincent Diepeveen2003/06/22 05:25 PM
                              New Silicon Insider ArticleJosé Javier Zarate2003/06/22 06:55 PM
                            New Silicon Insider ArticleAnonymous2003/06/23 08:59 AM
        New Silicon Insider ArticlePaul DeMone2003/06/19 06:53 PM
          New Silicon Insider ArticleBill Todd2003/06/19 07:53 PM
            New Silicon Insider ArticleDavid Wang2003/06/19 08:08 PM
              New Silicon Insider ArticleBill Todd2003/06/20 01:28 AM
                New Silicon Insider ArticleDavid Wang2003/06/20 10:35 AM
                  New Silicon Insider ArticlePaul DeMone2003/06/20 11:29 AM
                    New Silicon Insider ArticleBill Todd2003/06/20 06:10 PM
                      New Silicon Insider ArticleMarc M.2003/06/21 05:06 AM
                        New Silicon Insider ArticleBill Todd2003/06/21 11:07 AM
                  New Silicon Insider ArticleBill Todd2003/06/20 06:01 PM
                    New Silicon Insider ArticleDavid Wang2003/06/20 06:52 PM
                      New Silicon Insider ArticleBill Todd2003/06/20 07:53 PM
                        New Silicon Insider ArticleDavid Wang2003/06/20 08:14 PM
                          New Silicon Insider ArticleVincent Diepeveen2003/06/20 08:52 PM
                            New Silicon Insider ArticleMarc M.2003/06/21 07:16 AM
                              New Silicon Insider ArticleVincent Diepeveen2003/06/22 04:24 PM
                          New Silicon Insider ArticleSingh, S.R.2003/06/21 03:39 AM
                            New Silicon Insider ArticleDavid Wang2003/06/21 08:10 AM
                          IPF CompilersNate Begeman2003/06/21 09:10 AM
                            IPF CompilersPaul DeMone2003/06/21 09:45 AM
                        Use ILP to extract more ILPPaul DeMone2003/06/20 10:48 PM
            New Silicon Insider ArticlePaul DeMone2003/06/20 08:06 AM
              New Silicon Insider ArticleSingh, S.R.2003/06/20 09:41 AM
                New Silicon Insider ArticleDavid Kanter2003/06/21 03:34 PM
                  New Silicon Insider ArticlePaul DeMone2003/06/22 02:22 PM
              New Silicon Insider ArticleBill Todd2003/06/20 05:52 PM
              New Silicon Insider ArticleMarc M.2003/06/21 07:54 AM
    New Silicon Insider ArticleDaniel Gustafsson2003/06/19 11:12 AM
    New Silicon Insider ArticlePaul DeMone2003/06/20 02:20 PM
  New Silicon Insider ArticleBryan Gregory2003/06/20 01:14 PM
    New Silicon Insider Articlemas2003/06/20 01:43 PM
  New Silicon Insider ArticlePaul DeMone2003/06/25 10:29 AM
    New Silicon Insider ArticleJosé Javier Zarate2003/06/25 10:43 AM
      New Silicon Insider ArticlePaul DeMone2003/06/25 10:52 AM
    lol, amazing coincidence :-) (NT)mas2003/06/25 03:15 PM
  New Silicon Insider ArticleYoav2015/04/01 03:43 AM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell purple?