4 ms·
The m4 has 6 efficiency cores and 4 performance cores. This is 2 efficiency cores more than the previous generations, and the same number of p-cores, thus highe
by freehorse 2y ago
The m4 has 6 efficiency cores and 4 performance cores. This is 2 efficiency cores more than the previous generations, and the same number of p-cores, thus higher e to p core ratio, which can explain a large part of the increase in power efficiency. Not to say that otherwise there is nothing remarkable here, of course there is, but if the author found a 30% increase in efficiency compared to m2 while they claim they expected 4-10% after 2 generations of chips, it could be because of that.
The m4 pro has 4 e-cores and 6-8 p-cores, hence I would not expect similar increase.
- madeofpalk 2y agoIIRC as well, the M3 chips had an odd efficient to performance core ratio that’s not present in the M4, which is slightly interesting
- ghshephard 2y agoThat would explain improving performance, but I don't actually understand how that would improve efficiency. Particularly at the high end where they quote 6.74 Gflops/W .
- wtallis 2y agoIf a higher proportion of the total performance is coming from efficiency cores, it is reasonable to expect overall efficiency to be improved.
- freehorse 2y agoExactly this ^ In particular, under some ideal, unrealistic assumptions to simplify things, and denoting n the number of E-cores, E the efficiency and W_e the power consumption of each e-core, while respectively denoting m the number of each P-cores, P the efficiency and W_p the power consumption of each p-core, where E>P, we can calculate the express EFF of the cpu as EFF = (n*E*W_e + m*P*W_p)/(n*W_e + m*W_p) = (n*E*W_e - n*P*W_e + n*P*W_e + m*P*W_p)/(n*W_e + m*W_p) = (E-P)*n*W_e/(n*W_e + m*W_p) + P = (E-P)/(1 + (m/n)*(W_p/W_e)) + P which shows that the energy efficiency of the CPU increases monotonically as a function of the ratio of e to p cores n/m.