is precached supposed to preload iotrace files? about precached HOT 2 CLOSED

Yes! It is intentionally done this way, since we don't want to wait for the disk to fetch a trace log.
If the trace logs would not be cached, online-prefetching would not work as expected!

Background

If precached detects a fork() and subsequent exec() system call, it will hash the new process' file name and its command line parameters, and then search all trace logs looking for this specific hash value. If such a trace log of a previous program execution does exist, precached will initiate a replay of this trace log. This won't be as effective as loading the process' files ahead of time, but it at least may help a little bit. Especially if said process does a lot of "disk read"-computation-"disk read"-computation... cycles, online-prefetching may improve the startup performance considerably.

Benchmark of LibreOffice Calc:
Loaded ahead of time: 4 major page faults
Loaded with precached online-prefetching enabled: 257 major page faults
Loaded without precached: 1323 major page faults

from precached.

Okay that makes sense.

from precached.