Date: Mon, 14 Jul 2008 05:40:05 GMT From: Wayne Sierke <ws@au.dyndns.ws> To: freebsd-doc@FreeBSD.org Subject: Re: docs/125587: FAQ entry 5.13 -- adjustion is not an English word; tunable? Message-ID: <200807140540.m6E5e5Hf060446@freefall.freebsd.org>
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The following reply was made to PR docs/125587; it has been noted by GNATS. From: Wayne Sierke <ws@au.dyndns.ws> To: Mike Small <smallm@panix.com> Cc: bug-followup@freebsd.org Subject: Re: docs/125587: FAQ entry 5.13 -- adjustion is not an English word; tunable? Date: Mon, 14 Jul 2008 15:05:22 +0930 On Mon, 2008-07-14 at 03:16 +0000, Mike Small wrote: > Secondly, the same paragraph also uses the word "tunable" as a noun. > Is this a term people use in BSD? I mean, it's clear what's meant > from the context, but using "variable" or "sysctl variable", as is > done in the first paragraph, seems clearer and less strange to me. My understanding is that the term 'tunable' is used to refer to sysctl variables that can only be set at boot - i.e. are read-only at run-time. How about this?: The FreeBSD kernel limits the number of processes that may exist at one time. The default limit is based on the kern.maxusers sysctl(8) variable. kern.maxusers also affects various other in-kernel limits, such as network buffers (see this earlier question). If your machine is heavily loaded, you probably want to increase kern.maxusers. This will increase these other system limits in addition to the maximum number of processes. To adjust the kern.maxusers value, see the File/Process Limits section of the Handbook. (While that section refers to open files, the same limits apply to processes.) If your machine is lightly loaded and you are simply running a very large number of processes, you can adjust this with the kern.maxproc tunable. The value of this sysctl ´variable¡ is set at boot time and can only be changed by placing an appropriate entry in /boot/loader.conf and rebooting. If a large number of processes need to be run by a single user, kern.maxprocperuid should also be modified. Its maximum value should be one less than the kern.maxproc value because one system program, init(8), must always be running. For more information about setting tunables see the loader.conf(5) manual page. To make a sysctl change permanent place the proper value in /etc/sysctl.conf. More information about system tuning with sysctl(8) can be found at the Tuning with sysctl section of the Handbook. I'm not sure about the veracity of the "kern.maxprocperuid should be one less than kern.maxproc" statement. Does anyone know about this?
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