4 ms·

Idle CPUs use much less power, so no its not wasted in that sense.

vbezhenar 4y ago
Let's say we have CPU with $500 cost which consumes 100W. 1 kWh is $0.1. Case 1: we used this CPU for year with 1% average load. We paid $500 + 365 * 24h * 100W * 1% * $0.1 = $500 + $876 = $1 376. Case 2: we used this CPU for year with 100% average load. We paid $500 + 365 * 24h * 100W * 100% * $0.1 = $500 + $87 600. Case 3: like case 2, but we have cheap electricity with $0.01 for kWh. We will pay $500 + $8 760. In any case CPU cost itself is tiny compared to energy price. So we can consider CPU cost is zero and all computations just require spending electricity. So when some project asks to use your CPU at idle times, they're asking to use your electricity. And that's about it. You're donating electricity. It would be wrong to think that they're asking to use CPU which is not used anyway. Now whether you want to donate electricity or not is another matter. But one should clearly understand what he does. Edit: I forgot to divide by 1000, so those numbers are completely off, sorry.
- NavinF 4y ago
  > $500 + $87 600 100W * $0.10/kWh * 1 year = $87.66 You forgot to convert Wh to kWh. Google can evaluate the LHS in one step. That aside, I agree. The price difference is even larger with 400W GPUs and data center bills which include cooling in the electricity cost. Initial cost matters very little vs efficiency.
  - vbezhenar 4y ago
    Well, I guess that my conclusions were completely wrong for home usage. Spending $87 vs $8 per year is not a big deal and $500 CPU cost now dominates the total cost. So it makes sense to donate idle CPU time if you're fine with extra heat and some extra wear.
    - NavinF 4y ago
      IMO the “extra wear” is insignificant. Electromigration causes negligible wear compared to the thermal cycling of a typical gaming workload on a desktop GPU. Your conclusion was correct even if the math was off.
    - implements 4y ago
      It was well worth making the point, though. I recently bought a 2nd hand Intel NUC as a potential home server. Came with Ubuntu and used about 10 watt on idle. Put OpenBSD on it and it now draws 20 watt - I assume because OBSD is much less aggressive about idling. That’s about £3 per month extra on electricity if run 24/7.
      - NavinF 4y ago
        Ehh normally you’d want a home server to have a handful of SATA ports and enough PCIe lanes for a SAS card and GPU. If you’re spending 5W per HDD and hopefully in the future hundreds of watts for video transcoding, 20W for everything else is no big deal. Anyway I’ve never used OpenBSD, but you can probably mess with the CPU governor settings to make it idle more aggressively.

Let's say we have CPU with $500 cost which consumes 100W. 1 kWh is $0.1. Case 1: we used this CPU for year with 1% average load. We paid $500 + 365 * 24h * 100W * 1% * $0.1 = $500 + $876 = $1 376. Case 2: we used this CPU for year with 100% average load. We paid $500 + 365 * 24h * 100W * 100% * $0.1 = $500 + $87 600. Case 3: like case 2, but we have cheap electricity with $0.01 for kWh. We will pay $500 + $8 760. In any case CPU cost itself is tiny compared to energy price. So we can consider CPU cost is zero and all computations just require spending electricity. So when some project asks to use your CPU at idle times, they're asking to use your electricity. And that's about it. You're donating electricity. It would be wrong to think that they're asking to use CPU which is not used anyway. Now whether you want to donate electricity or not is another matter. But one should clearly understand what he does. Edit: I forgot to divide by 1000, so those numbers are completely off, sorry.

NavinF 4y ago
> $500 + $87 600 100W * $0.10/kWh * 1 year = $87.66 You forgot to convert Wh to kWh. Google can evaluate the LHS in one step. That aside, I agree. The price difference is even larger with 400W GPUs and data center bills which include cooling in the electricity cost. Initial cost matters very little vs efficiency.
- vbezhenar 4y ago
  Well, I guess that my conclusions were completely wrong for home usage. Spending $87 vs $8 per year is not a big deal and $500 CPU cost now dominates the total cost. So it makes sense to donate idle CPU time if you're fine with extra heat and some extra wear.
  - NavinF 4y ago
    IMO the “extra wear” is insignificant. Electromigration causes negligible wear compared to the thermal cycling of a typical gaming workload on a desktop GPU. Your conclusion was correct even if the math was off.
  - implements 4y ago
    It was well worth making the point, though. I recently bought a 2nd hand Intel NUC as a potential home server. Came with Ubuntu and used about 10 watt on idle. Put OpenBSD on it and it now draws 20 watt - I assume because OBSD is much less aggressive about idling. That’s about £3 per month extra on electricity if run 24/7.
    - NavinF 4y ago
      Ehh normally you’d want a home server to have a handful of SATA ports and enough PCIe lanes for a SAS card and GPU. If you’re spending 5W per HDD and hopefully in the future hundreds of watts for video transcoding, 20W for everything else is no big deal. Anyway I’ve never used OpenBSD, but you can probably mess with the CPU governor settings to make it idle more aggressively.