Investigating Performance of Multi-Threading on Zen 3 and AMD Ryzen 5000

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• warpuck - Friday, December 25, 2020 - link

  With a R 5 1600 it makes about 5-6% difference in usable clock speed. (200-250 Mhz) and also with temperature. With a R 7 3800X it is not as noticeable.
  If you reduce the background operations while gaming with either CPU.
  I don't know about recent game releases but older ones only use 2-4 cores (threads) so clocking the R 5 1600 @ 3750 (SMT on) Mhz vs 3975 Mhz (SMT off) does make a difference on frame rates

• whatthe123 - Saturday, December 5, 2020 - link

  it doesn't make much of a difference unless you go way past the TDP and have exotic cooling.
  
  these CPUs are already boosting close to their limits at stock settings to maintain high gaming performance.

• 29a - Saturday, December 5, 2020 - link

  There is a lot of different scenarios that would be interesting to see. I would like to see some testing with a dual core chip 2c/4t.

• Netmsm - Thursday, December 3, 2020 - link

  good point

• Wilco1 - Friday, December 4, 2020 - link

  I think that 5% area cost for SMT is marketing. If you only count the logic that is essential for SMT, then it might be 5%. However many resources need to be increased or doubled. Even if that helps single-threaded performance, it still adds a lot of area that you wouldn't need without SMT.
  
  Graviton 2 proves that 2 small non-SMT cores will beat one big SMT core on multithreaded workloads using a fraction of the silicon and power.

• peevee - Monday, December 7, 2020 - link

  Except they are not faster, but whatever.

• RickITA - Thursday, December 3, 2020 - link

  Several compute applications do not need hyper-threading. A couple of official references:
  1. Wolfram Mathematica: "Mathematica’s Parallel Computing suite does not necessarily benefit from hyper-threading, although certain kernel functionality will take advantage of it when it provides a speedup." [source: https://support.wolfram.com/39353?src=mathematica]. Indeed Mathematica automatically set-up a number of threads equal to the number of physical cores of the CPU.
  2. Intel MKV library. "Hyper-Threading Technology (HT Technology) is especially effective when each thread is performing different types of operations and when there are under-utilized resources on the processor. Intel MKL fits neither of these criteria as the threaded portions of the library execute at high efficiencies using most of the available resources and perform identical operations on each thread. You may obtain higher performance when using Intel MKL without HT Technology enabled." [source: https://software.intel.com/content/www/us/en/devel...].
  
  BTW Ian: Wolfram Mathematica has a benchmark mode [source: https://reference.wolfram.com/language/Benchmarkin...], please consider to add it to your test suite. Or something with Matlab.

• realbabilu - Thursday, December 3, 2020 - link

  Apparently intel mkl and Matlab that uses intel mkl only allowing AMD uses non AVX2 library only. Only Linux with fake cpu preloaded library could go around this.
  https://www.google.com/amp/s/simon-martin.net/2020...

• RickITA - Thursday, December 3, 2020 - link

  Not a matlab user, but this is no longer true since version 2020a. Source: https://www.extremetech.com/computing/308501-cripp...

• leexgx - Saturday, December 5, 2020 - link

  The "if not Intel genuine cpu" disabled all optimisations (this rubbish has been going on for years only 2020 or 2019 where they are actually fixing there code to detect if AVX is available, even BTRFS had this problem it wouldn't use hardware acceleration if it wasn't on an intel CPU, again lazy coding )