Best way to "renice" a process by name?
brett at lariat.net
Tue Sep 26 08:56:54 PDT 2006
I'm working with a machine that's operating as a NAT router and
recursive DNS resolver and is also running the Squid disk cache.
Squid, in turn, spawns the "diskd" daemon, which does disk accesses
on behalf of Squid. When Squid spawns diskd, it gives it a priority
level 6 greater than itself. In other words, if Squid is launched
normally, it gets a priority of 2 (normal) while diskd gets a
priority of -4 (very high).
Unfortunately, diskd is not an efficient user of CPU (it seems to
be polling for I/O completion) and is starving other processes on
the machine (for example, natd) which need to operate in near real time.
I'd like to keep diskd running on that machine, because having disk
access done by a separate process is very efficient -- even more so
if the system uses SMP. But I need to re-prioritize Squid and diskd
to keep the rest of the machine functional. In particular, I'd like
to nice Squid down by 1 (so that natd and named have priority over
it) and have diskd run at standard priority (so that it can't
starve other processes). This will keep diskd at a higher priority
than Squid itself, which in turn will hopefully prevent message
queues from overflowing.
Reducing Squid's priority is simple; I can just edit the script
that starts Squid so that /usr/bin/nice is used to invoke it. But
taming diskd is more difficult, because diskd is a child process of
Squid. I have to make sure it has started (which may require a
delay loop), find out its PID, and then "renice" it by whatever
increment is required to get it to the system's standard priority
(2 by convention). Is there a "renice by name" utility for FreeBSD
(sort of an equivalent of "killall")? I could gin one up, but since
this seems like something that people would want to do frequently,
find it hard to believe that someone hasn't already written one.
More information about the freebsd-questions