Exploiting the sleep mode

It has been noted that when a platform has a low-power idle state, it may be sensible to sacrifice energy in the short-term in order to complete an application quickly and enter the low-power idle state [26]. Figure 8 shows the effect of this analysis for compression and sending of text. Receive/decompression exhibits similar, but less-pronounced variation for different idle powers. It is interesting to note that, assuming a low-power idle mode can be entered once compression is complete, one's choice of compression strategies will vary. With its 1Watt of idle power, the Skiff would benefit most from zlib compression. A device which used negligible power when idle would choose the LZO compressor. While LZO does not compress data the most, it allows the system to drop into low-power mode as quickly as possible, using less energy when long idle times exist. For web data (not shown due to space constraints) the compression choice is LZO when idle power is low. When idle power is one Watt, bzip2 energy is over 25% more energy efficient than the next best compressor.

Figure 8: Compression + Send energy consumption with varying sleep power (Text data)