Cannot reproduce with microcode 0xc6

By: Adrian (a.delete@this.acm.org), February 27, 2019 5:02 am
Room: Moderated Discussions
Travis Downs (travis.downs.delete@this.gmail.com) on February 26, 2019 3:23 pm wrote:
>
> Maybe there was some microcode change which reduced performance
> for this type of load? Or maybe my box is just weird somehow?


Here you have the results for a new Coffee Lake with microcode 0x9a, which I assume is still older than yours.


Just looking at the numbers I cannot say whether the distribution is multimodal, as I see similar quantities of most values between 3 and 9.

What is certain that there are no large 18 cycle values, which were present for the Kaby Lake with an old microcode, but also absent for the Skylake with a newer microcode.


For all 3 computers I have run the test a few times and the results looked mostly the same.

A weird thing was that if the browser remained open (with RWT) while running the test, randomly a few values were lower than usually, i.e. 1.x and once I have seen a value that looked like a negative number displayed as an unsigned value, so some sort of underflow must have occurred. I believe that those were artifacts due to thread migration between cores on a non-idle CPU.


On this Coffee Lake I have run the test many times and it usually looked like this. However, one single time, a single value of all displayed values was around 18 cycles.

So whatever happens which results in that time, probably also happens on these processors with a newer microcode, but only very seldom, not at every test as on the one with an old microcode.




model name : Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
microcode : 0x9a

Testing method asm
0 64 128 192 256 320 384 448 512 576 640 704 768 832 896 960 1024 1088 1152 1216 1280 1344 1408 1472 1536 1600 1664 1728 1792 1856 1920 1984 2048
0 3.1 3.6 7.9 8.5 8.9 8.1 8.1 7.5 7.1 7.1 6.6 6.3 6.5 6.2 5.9 6.1 6.3 6.0 6.3 5.7 5.9 5.9 6.0 6.0 6.1 6.5 7.1 8.5 8.6 8.6 8.8 8.7 8.7
64 8.0 3.8 3.6 7.7 8.4 8.4 7.9 8.0 7.6 7.1 7.1 6.7 6.7 6.2 6.1 5.8 6.4 6.4 6.1 5.9 5.8 5.9 5.9 5.9 6.0 6.1 6.5 7.2 8.5 8.6 9.1 9.4 8.6
128 8.7 8.1 3.7 3.6 8.0 9.0 8.3 8.0 7.9 7.4 6.7 7.1 6.5 6.4 6.0 6.7 5.9 6.5 6.4 6.2 5.7 5.8 5.9 5.9 6.0 6.0 6.1 6.5 7.2 8.9 8.6 8.7 8.7
192 8.6 8.8 8.4 3.7 3.7 8.3 8.1 8.4 8.0 8.1 7.5 7.1 7.1 6.7 6.5 6.1 6.1 5.9 6.3 6.3 6.0 5.9 5.8 5.8 6.0 6.0 6.0 6.2 6.5 7.1 8.6 8.5 8.7
256 8.3 8.5 8.8 8.0 4.1 3.7 8.0 8.5 8.4 8.1 8.1 7.4 7.1 7.1 6.5 6.4 6.0 6.1 5.9 6.6 6.4 6.1 5.9 5.8 5.9 5.9 6.0 6.0 6.1 6.5 7.4 8.7 8.7
320 8.2 8.3 9.3 8.5 7.7 3.7 3.7 8.1 8.2 8.4 7.9 8.0 7.5 7.2 7.2 6.6 6.3 6.2 6.1 5.9 6.2 6.4 6.1 5.9 5.8 5.7 5.9 5.9 6.0 6.1 6.4 7.2 8.8
384 7.7 8.2 8.3 8.4 8.9 8.0 3.6 3.6 7.9 8.4 8.4 8.0 8.0 8.0 7.1 7.1 6.5 6.4 6.0 6.0 6.0 6.4 6.4 6.0 5.9 5.7 5.9 5.9 5.9 5.9 6.2 6.8 7.2
448 7.6 7.8 8.0 8.4 8.4 8.9 8.5 3.7 3.6 8.4 8.6 8.3 7.9 8.4 7.5 7.0 7.1 6.6 6.3 6.0 6.2 6.0 6.4 6.4 6.1 5.8 5.9 5.8 5.9 6.0 6.0 6.1 6.5
512 7.4 7.4 7.7 8.1 8.3 8.4 9.1 7.9 3.7 3.6 8.1 8.4 8.3 7.9 8.1 7.4 7.1 7.2 6.4 6.3 6.0 6.4 5.9 6.2 6.4 6.1 5.8 5.9 3.0 3.0 6.0 6.0 6.1
576 7.0 7.3 7.4 7.8 8.2 8.4 8.0 8.9 7.9 3.7 3.5 7.9 8.3 8.3 7.8 8.0 7.3 7.0 7.1 6.8 6.3 6.0 6.4 6.0 5.1 6.2 6.0 5.9 5.8 5.8 5.9 5.9 6.0
640 6.6 7.1 7.3 7.5 7.7 8.2 8.3 9.1 8.8 8.3 3.7 3.6 8.2 8.4 8.4 8.0 8.0 7.4 7.1 7.1 6.5 6.4 6.0 6.1 5.9 6.3 6.3 6.1 5.9 5.8 5.7 5.9 6.0
704 6.5 6.5 7.1 7.3 7.5 7.7 8.1 8.3 8.3 8.8 7.9 3.7 3.6 8.0 8.4 8.4 8.0 8.0 7.4 7.2 7.0 6.6 6.5 6.2 6.1 5.9 6.4 6.4 6.1 5.9 5.7 5.7 5.9
768 6.4 3.2 6.5 7.1 7.4 7.5 7.7 8.2 8.3 8.4 8.9 8.1 3.7 3.6 8.1 8.3 8.1 7.9 7.8 7.4 6.9 7.0 6.5 6.3 6.0 6.1 6.0 6.3 6.3 5.9 5.9 5.9 5.9
832 6.1 6.3 6.8 6.6 7.1 7.3 7.3 7.5 8.2 8.4 8.4 8.8 8.2 3.7 3.6 8.2 8.5 8.3 7.9 8.0 7.5 6.9 7.1 6.5 6.4 6.2 3.0 2.9 6.3 6.4 3.1 5.9 6.1
896 6.1 6.1 6.2 6.9 3.3 7.1 7.3 7.5 7.8 8.0 6.7 8.5 9.2 8.2 3.6 3.7 8.1 8.3 8.4 8.1 8.1 7.5 6.9 7.1 6.6 6.3 6.1 6.1 5.9 6.3 6.4 6.0 5.9
960 6.6 6.1 6.1 6.4 6.4 6.5 7.0 7.5 7.3 7.8 8.1 8.3 8.6 8.9 8.3 3.7 3.6 8.6 8.4 8.4 8.0 8.1 7.4 7.5 7.1 6.4 6.3 6.0 6.1 5.9 6.4 6.4 6.1
1024 7.0 6.3 6.3 6.0 6.2 6.7 6.6 7.1 7.4 7.5 7.7 8.2 8.2 8.3 8.8 8.2 3.7 3.7 8.0 8.4 8.4 7.9 8.0 7.6 7.0 7.2 6.6 6.7 6.0 6.0 5.9 6.3 6.3
1088 5.9 6.9 6.4 6.0 6.0 6.2 6.5 6.6 6.9 7.4 7.5 7.5 8.2 8.2 8.3 8.5 7.9 3.8 3.6 9.1 8.2 8.3 8.0 7.9 7.4 7.1 7.2 6.5 6.3 6.1 6.1 5.8 6.7
1152 5.9 5.8 6.8 6.4 6.1 6.1 6.1 6.5 6.6 7.1 7.3 7.4 7.8 8.2 8.0 8.4 8.7 8.3 3.6 3.7 8.1 8.5 8.3 8.3 8.0 7.4 7.0 7.2 6.5 6.4 6.0 6.0 5.9
1216 5.9 5.8 5.8 6.8 6.4 6.1 6.1 6.4 6.5 6.5 7.1 7.3 7.5 7.8 8.2 8.2 8.4 8.9 8.1 3.7 3.7 7.8 8.5 8.4 7.9 8.0 7.4 7.7 7.2 6.5 6.3 6.0 6.1
1280 5.9 5.9 5.9 5.9 6.9 6.6 6.1 6.1 6.2 6.8 6.6 7.0 7.3 7.5 7.7 8.1 8.3 8.5 9.0 8.4 3.8 3.7 8.2 8.5 8.4 8.0 7.9 7.3 7.0 7.2 6.6 6.3 6.2
1344 5.9 5.9 5.9 5.9 5.8 6.7 6.6 6.1 6.1 6.3 6.4 6.6 7.1 7.4 7.5 8.1 8.1 8.3 8.4 8.9 8.1 3.7 3.7 8.3 8.4 8.4 8.0 8.1 7.3 7.3 7.6 6.6 6.4
1408 6.0 6.0 5.9 5.9 5.9 5.9 6.6 6.3 6.2 6.2 6.3 6.5 6.6 7.1 7.3 7.3 7.7 8.2 8.2 8.5 8.9 8.0 3.8 3.6 8.2 8.4 8.4 8.1 8.0 7.5 7.5 7.2 6.5
1472 6.1 6.0 6.0 5.9 5.9 5.8 5.8 6.6 6.6 6.1 6.1 6.2 6.6 6.6 7.0 7.4 7.4 7.8 8.0 8.3 8.5 8.8 8.5 3.7 3.6 7.8 8.3 8.3 8.1 7.9 7.5 7.1 7.1
1536 6.3 6.1 6.0 6.0 5.9 5.9 5.9 5.8 6.9 6.6 6.1 6.1 6.2 6.5 6.5 7.0 7.4 7.5 7.8 8.1 8.4 8.5 8.9 9.0 3.7 3.6 8.1 8.5 8.4 8.1 8.0 7.2 7.1
1600 7.0 6.3 6.1 6.0 5.9 5.9 5.9 5.9 5.8 6.8 6.5 6.1 6.1 6.3 6.5 6.6 7.0 7.3 7.5 7.5 8.2 8.2 8.5 8.6 7.6 3.7 3.7 8.0 8.0 8.4 8.1 8.0 7.3
1664 8.0 7.0 6.3 6.1 6.0 5.9 5.9 5.8 5.9 5.9 6.8 6.4 6.1 6.1 6.3 6.6 6.4 7.0 7.4 7.4 7.3 8.0 8.2 8.4 8.9 8.3 3.7 3.7 8.1 8.3 8.4 8.0 8.1
1728 9.1 8.0 7.0 6.3 6.1 6.0 5.9 6.0 5.9 5.9 5.9 6.7 6.3 6.1 6.1 6.3 6.4 6.5 7.1 7.3 7.6 7.8 7.9 8.3 8.5 8.8 8.3 3.7 3.5 8.0 8.4 8.3 8.0
1792 9.0 9.1 8.1 6.9 6.3 6.1 6.0 5.9 5.9 5.9 5.9 5.9 6.7 6.4 6.1 6.1 6.1 6.7 6.6 7.1 7.4 7.5 7.8 8.2 8.3 8.5 8.9 8.3 4.1 3.5 8.2 8.4 8.3
1856 9.1 9.2 9.1 8.1 6.9 6.3 6.1 6.0 5.9 5.9 5.9 5.9 5.9 6.7 6.6 6.1 5.9 6.2 6.4 6.6 7.0 7.3 7.5 7.7 8.2 8.3 8.2 9.0 8.3 3.7 3.7 7.9 8.3
1920 9.1 9.0 9.2 9.1 8.0 6.9 6.3 6.1 6.0 5.9 5.9 5.8 5.8 5.9 6.7 6.4 6.1 6.1 6.3 6.5 6.6 7.2 7.3 7.5 7.6 8.1 8.2 8.5 8.7 8.0 3.6 3.6 8.0
1984 9.4 9.1 9.0 8.9 9.0 8.4 7.3 6.4 6.1 5.9 5.9 6.2 6.2 5.9 5.8 6.6 6.4 6.1 6.1 6.2 6.5 6.6 7.0 7.7 7.4 7.8 8.2 8.4 8.6 8.8 8.1 3.7 4.0
2048 9.1 9.1 9.1 9.1 9.0 8.9 8.0 6.9 6.3 6.0 6.0 5.9 5.9 5.9 5.8 5.9 6.8 6.2 6.0 6.1 6.3 6.5 6.5 7.1 7.3 7.4 7.8 8.0 8.2 8.2 8.7 8.2 3.7
2112 9.0 8.9 9.0 9.0 9.0 9.0 9.6 8.1 7.3 6.3 6.0 6.0 5.9 5.8 5.9 5.9 5.9 6.6 6.4 6.4 6.0 6.2 6.6 6.6 7.0 7.7 7.5 7.7 8.1 8.2 8.3 8.8 8.4
2176 9.2 9.2 9.0 8.9 9.0 9.0 9.8 9.1 8.0 6.8 6.3 6.1 5.9 6.0 5.9 5.9 5.9 6.2 6.8 6.6 5.9 6.0 6.3 6.5 6.5 7.0 7.3 7.5 7.7 8.1 8.2 8.3 9.2
2240 9.1 8.9 9.1 9.0 9.1 9.1 8.9 9.0 9.0 8.0 7.0 6.3 6.0 4.5 5.9 5.9 5.9 5.8 5.8 6.8 6.6 6.1 6.1 6.3 6.8 6.6 7.0 7.3 7.5 7.7 8.1 8.3 9.0




< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/20 02:44 PM
  Bridges? Wells? (NT)Micahel S2017/12/20 03:53 PM
    Bridges? Wells? (NT)Travis2017/12/20 04:46 PM
      That should say "huh"? (NT)Travis2017/12/20 04:46 PM
        That should say "huh"?Jeff S.2017/12/20 05:11 PM
          That should say "huh"?Travis2017/12/20 06:34 PM
    Bridges? Wells?Jeff S.2017/12/20 05:17 PM
      Bridges? Wells?Travis2017/12/20 06:37 PM
    Bridges, Wells - positiveMichael S2017/12/21 02:52 AM
      Bridges, Wells - positiveTravis2017/12/21 09:35 AM
        Bridges, Wells - positiveMichael S2017/12/21 10:00 AM
  Why does writing to non-sequential lines in L2 perform so poorly?Linus Torvalds2017/12/20 06:18 PM
    Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/20 06:54 PM
      Why does writing to non-sequential lines in L2 perform so poorly?Linus Torvalds2017/12/21 12:12 PM
        Why does writing to non-sequential lines in L2 perform so poorly?anon2017/12/22 03:29 AM
          Why does writing to non-sequential lines in L2 perform so poorly?Linus Torvalds2017/12/22 01:16 PM
            Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/23 08:48 PM
            Why does writing to non-sequential lines in L2 perform so poorly?Travis Downs2020/06/13 03:18 PM
              Why does writing to non-sequential lines in L2 perform so poorly?John D. McCalpin2020/06/18 12:50 PM
                Why does writing to non-sequential lines in L2 perform so poorly?Travis Downs2020/06/18 05:32 PM
                  Why does writing to non-sequential lines in L2 perform so poorly?Travis Downs2020/06/18 05:34 PM
    Why does writing to non-sequential lines in L2 perform so poorly?anon.12017/12/21 06:09 PM
      Why does writing to non-sequential lines in L2 perform so poorly?Linus Torvalds2017/12/22 01:20 PM
        Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/24 02:09 PM
  Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/20 08:52 PM
    Why does writing to non-sequential lines in L2 perform so poorly?Adrian2017/12/21 12:09 AM
      Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/21 09:23 AM
    Why does writing to non-sequential lines in L2 perform so poorly?-.-2017/12/27 03:53 AM
      Why does writing to non-sequential lines in L2 perform so poorly?-.-2017/12/27 03:53 AM
        Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/27 04:18 PM
  Why does writing to non-sequential lines in L2 perform so poorly?Etienne2017/12/21 02:36 AM
    Why does writing to non-sequential lines in L2 perform so poorly?Michael S2017/12/21 02:58 AM
      Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/21 09:26 AM
        Michael ignore my last question - saw your other reply (NT)Travis2017/12/21 09:27 AM
  Why does writing to non-sequential lines in L2 perform so poorly?Nksingg2017/12/26 06:47 AM
    Why does writing to non-sequential lines in L2 perform so poorly?David Kanter2017/12/26 11:48 AM
    Why does writing to non-sequential lines in L2 perform so poorly?Travis2017/12/27 04:33 PM
  Cannot reproduce with microcode 0xc6Travis Downs2019/02/26 04:23 PM
    Cannot reproduce with microcode 0xc6Adrian2019/02/26 09:35 PM
    Cannot reproduce with microcode 0xc6Adrian2019/02/26 10:07 PM
    Cannot reproduce with microcode 0xc6Adrian2019/02/27 05:02 AM
      Cannot reproduce with microcode 0xc6Travis Downs2019/02/27 08:25 AM
        Cannot reproduce with microcode 0xc6Adrian2019/02/28 01:16 AM
          Cannot reproduce with microcode 0xc6Travis Downs2019/03/07 06:51 PM
        Cannot reproduce with microcode 0xc6Adrian2019/02/28 09:54 AM
          Cannot reproduce with microcode 0xc6Travis Downs2019/03/24 06:34 PM
    Cannot reproduce with microcode 0xc6Travis Downs2019/02/27 03:20 PM
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