kern/70649: system clock slows down when heavily loaded
s2liang at uwaterloo.ca
Wed Aug 18 19:30:24 PDT 2004
>Synopsis: system clock slows down when heavily loaded
>Arrival-Date: Thu Aug 19 02:30:23 GMT 2004
>Originator: Suihong Liang
Univeristy of Waterloo
FreeBSD hurricane.cs.uwaterloo.ca 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #2: Fri Jul 2 16:25:54 GMT 2004 root at hurricane.cs.uwaterloo.ca:/usr/src/sys/i386/compile/ORIGIN i386
It takes "SHORTER" time in scp a file while heavily loaded, in
fact, the receiver shows that it takes LONGER!
I think the kernel does not handle the system clock well when it is heavily loaded.
I've tried the built-in time, GNU time, and my simple home-brewed timer programs, same result was yielded.
1. cpu workload program can be a infinite loop program.
2. In my testing, I run 32 instances of such workload programs.
3. Use command "time" to time the scp in an ethernet environment. Do NOT trust the time reported by scp.
4. I used the same set of 30 files (each of 100MB).
5. reboot the sender after each set of scp is done.
More information about the freebsd-bugs