Hi! Heres a fun one on stable/10: This one works: [root at darkwatch] /data/blockd# cat test.d pid$target:libc*:memcpy:return { @[execname, ustack()] = count(); } END { trunc(@, 3); } This one however doesn't! [root at darkwatch] /data/blockd# cat test2.d pid$target:libc*:memcpy:entry { [execname] = quantize(arg2); }