I wanted to profile the memory usage of a script. Here's the output before it was running: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 15624 186660 39460 439052 0 0 0 2 1 1 0 0 100 0 Here's the output while the script is running, at the point where free memory was at its lowest value: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 15624 11464 40312 473524 0 0 0 2 1 1 0 0 100 0 So free memory dropped by about 175 MB, and I expected that buff would increase by that amount. But it seems the other columns changed by relatively negligible amounts - how is this possible? Am I interpreting this wrong, or is some memory just not being accounted for in this output?