If reading or writing a cache line of size 64 bytes to Flash requires 2.56 μJ and DRAM requires 0.5 nJ, and if idle power consumption for DRAM is 1.6 W (for 8 GB), how long should a system be idle to benefit from hibernating? Assume a main memory of size 8 GB.

Total DRAM memory = 1.6 * 8 * 10^9 Bytes J/seconds = 12.8*10^9 J/s ---1

Total energy required to read or write cache-line to Flash and DRAM = 2*64*( 2.56 *10^-6+0.5 *10^-9) J = 3.277*10^-4 J---2

The time a system will be idle is 2/1 = 2.56*10^-14 seconds

Explanation:

Here, the 2 and 1 in the last step corresponds to the answers from equation equation 1 and equation 2.