4 ms·
Is that true? I thought cores slept until they were needed. Or didn't clock as high if instruction load wasn't there to match. There is of course always some n
by abstractbarista 6y ago
Is that true? I thought cores slept until they were needed. Or didn't clock as high if instruction load wasn't there to match.
There is of course always some nominal minimum power consumption for a server to be on. But every instruction requires some additional amount of electron flow to execute.
- WrtCdEvrydy 6y agoDatacenter grade stuff won't sleep as conservatively as a desktop grade CPU.
- lucb1e 6y agoYou can configure it to do that, though. I don't run my hardware in a datacenter (I prefer hosting from home for various reasons) but my server's CPU is set to use the powersave governor.
- jeffbee 6y agoLet me put it a different way. There may exist two different programs that draw the same amount of power through the CPU but have different instructions-per-clock performance. The one with the higher IPC is getting all its extra instructions for free in energy terms. Look at it another way: if a machine is already in its highest power state, with all cores running, but only executing one thread per core, running another thread on each core may cost almost nothing in terms of energy but could boost instructions retired by a lot. The marginal cost of each instruction in compressed at the high end of utilization. The first instruction costs a lot, but after you're already running it the best thing you can do for efficiency is take utilization on that machine straight to 100%.