Date: Tue, 14 Nov 2006 23:56:45 +0000 From: Robin Becker <robin@reportlab.com> To: Damian Wiest <dwiest@vailsys.com> Cc: freebsd-questions@freebsd.org Subject: Re: sysv semaphores Message-ID: <455A57BD.3030006@jessikat.plus.net> In-Reply-To: <20061114231102.GF20235@dfwdamian.vail> References: <4559DF39.7070506@chamonix.reportlab.co.uk> <20061114224652.GE20235@dfwdamian.vail> <20061114231102.GF20235@dfwdamian.vail>
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Damian Wiest wrote: ......... >> You'll want to use either sysctl(8) to change the settings dynamically, or >> use /etc/sysctl.conf to modify the settings permanently. I'm not sure if >> there's a benefit to rolling a new kernel versus using sysctl.conf, or if >> things even work that way anymore. >> >> # sysctl -a | grep seminfo >> >> kern.seminfo.semmni=10 # number of semaphore identifiers >> kern.seminfo.semmns=60 # number of semaphores in system >> kern.seminfo.semmnu=30 # number of undo structures in system >> kern.seminfo.semmsl=60 # max number of semaphores per id >> kern.seminfo.semopm=100 # max number of operations per semop call >> kern.seminfo.semume=10 # max number of undo entries per process >> kern.seminfo.semusz=100 # size in bytes of undo structure >> kern.seminfo.semvmx=32767 # semaphore maximum value >> kern.seminfo.semaem=16384 # adjust on exit max value >> >> Those comments are from /usr/include/sys/sem.h >> >> -Damian > > Sorry, I forgot to mention a few things. > > You should become familiar with ipcs(1) as it will allow you to query > the current state of SysV IPC facilities. You'll probably find yourself > manually deleting semaphores depending on how well that extension cleans > up after itself during testing. > > IIRC, the kernel maintains some in-memory datastructures to keep track > of semaphores. I believe increasing the maximum number of semaphores > will take up a negligible amount of main memory. > > If you're interested, the "Design and Implementation of the 4.4 BSD > Operating System" (ISBN # 0201549794) has great coverage of this stuff. ........ thanks very much all very useful info. Someone else recommended looking at these options kern.ipc.semmap=180 kern.ipc.semmni=160 kern.ipc.semmns=210 kern.ipc.semmnu=180 kern.ipc.semmsl=210 kern.ipc.semopm=250 kern.ipc.semume=160 kern.ipc.semusz=92 kern.ipc.semvmx=32767 kern.ipc.semaem=16384 and on my 6.1 system I see these with sysctl -a | grep ipc, however, # sysctl -a | grep seminfo /usr/RL_HOME/users/robin: # I guess they've been renamed. -- Robin Becker
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