Date: Fri, 15 Jun 2001 02:09:19 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Mike Silbersack <silby@silby.com> Cc: Devin Butterfield <dbutter@wireless.net>, Alfred Perlstein <bright@rush.net>, Rajappa Iyer <rsi@panix.com>, hackers@FreeBSD.ORG Subject: Re: Sysadmin article Message-ID: <3B29D0BF.5D6BE93E@mindspring.com> References: <20010615001400.L23791-100000@achilles.silby.com>
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Mike Silbersack wrote: > Rather than a tuned configuration, what would be useful is > a script that would evaluate a system and give tuning hints. > This might be simple for someone familiar with shell scripting > or perl. It could do something like: [ ... Eliza program for FreeBSD ... ] Doing this is non-trivial. Many of the things they should have tuned can not be tuned except at compile time. Any object allocated out of a zone before the VM is started, such as inpcb's and tcpcb's, in order to render the objects pageable, are allocated from a zone which is not growable, and takes a static amount of kernel virtual address space. This is not obvious, unless you look very carefully at the code. Similarly, allocations wich must be able to occur at interrupt time, such as replacement mbuf's for ring buffer contents in ethernet drivers, similarly, must come from a static pre-allocation. By definition, you can not resize these things at runtime. Things in zones are type-stable, as well, which means that even if you don't use all of them, they are deducted from your total available memory, which might instead be better spent in buffer cache, directory lookup cache, or any of hundreds of other resources. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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