[RDDSK / WRDSK]
When the kernel maintains standard io statistics (>= 2.6.20): The [read / write] data transfer issued physically on disk (so writing to the disk cache is not accounted for). This counter is maintained for the application process that writes its data to the cache (assuming that this data is physically transferred to disk later on). Notice that disk I/O needed for swapping is not taken into account. Unfortunately, the kernel aggregates the data tranfer of a process to the data transfer of its parent process when terminating, so you might see transfers for (parent) processes like cron, bash or init, that are not really issued by them.
(Eu concordo que isso é lamentável. Especialmente dada a característica anunciada do topo de mostrar recursos usados até mesmo por processos que saíram em algum momento durante o intervalo de monitoramento, implementado usando contabilidade de processo, também conhecida como psacct ).