3 ms·

Hmm, does this affect power draw?

• AstralStorm 2y ago
  I believe the opcache is too small to really matter here to disable. Even though it's fast SRAM, it's not too many transistors. Performance loss will of course cause the task to run longer which increases total power usage. It makes much more sense to disable SMT instead first, with the performance losses being on par most of the time, while this bringing serious powwr savings.
  • skavi 2y ago
    I would assume the inverse relationship. That enabling the op cache would reduce power draw. Though I also wouldn’t be surprised if they’re always running the decoder.
    • p_l 2y ago
      The very reason for the Loop Buffer was to let decoder power down within tight loops, so I'd assume micro op cache would have similar effect, except with more impact on performance.
      • skavi 2y ago
        Very curious as to the typical strategy for implementing low power modes on things that are highly latency sensitive like a decoder. Like would whatever mechanism they’ve got behave well if fetches were alternating between cache hits and cache misses?
• Symmetry 2y ago
  Well, the decode used to use 15% of an x86 core's power budget but it hasn't grown as fast as the other structures so I'd guess more like 10% these days. So you're losing out on being able to turn off a small but noticeable part of your active power usage. But on the other hand fewer instructions executing means less active power draw in the rest of your core too. So it's not clear which way it goes in terms of Watts, but certainly you use more Jules.