To get a clear output for memory usage by each process:
ps -eo size,pid,user,command --sort -size | \
awk '{ hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }' |\
cut -d "" -f2 | cut -d "-" -f1