Date: Tue, 26 Sep 2006 22:22:52 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Brett Glass <brett@lariat.net> Cc: questions@freebsd.org Subject: Re: Best way to "renice" a process by name? Message-ID: <20060926192252.GG1863@gothmog.pc> In-Reply-To: <7.0.1.0.2.20060926090533.083a2a88@lariat.net> References: <7.0.1.0.2.20060926090533.083a2a88@lariat.net>
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On 2006-09-26 09:32, Brett Glass <brett@lariat.net> wrote: > 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. Maybe something like this helps? $ echo renice -n +10 -p `echo \`pgrep httpd\` | sed -e 's/ /,/g'` renice -n +10 -p 1023,656,655,654,653,652,610 $ There is always a fair chance you might attempt to renice a process which just happened to die, but this should be ok, unless you start seeing PIDs being recycled too fast :)
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