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Date:      Thu, 5 Dec 2002 13:36:28 +0300 (MSK)
From:      Varshavchick Alexander <alex@metrocom.ru>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        <freebsd-questions@FreeBSD.ORG>, <freebsd-hackers@FreeBSD.ORG>
Subject:   Re: maxusers and random system freezes
Message-ID:  <Pine.GSO.4.33.0212051315320.7912-100000@apache.metrocom.ru>
In-Reply-To: <3DEF2573.D8C66C11@mindspring.com>

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On Thu, 5 Dec 2002, Terry Lambert wrote:

...

> > Because it's not defined in the custom
> > server's kernel then it's value default to 256 (FreeBSD 4.5-STABLE), which
> > makes the KVA space to occupy 1G. Then if I make KVA_PAGES=512 (KVA space
> > 2G), will it solve the problem for this particular server having 4G of
> > phisical memory, or must KVA_PAGES be 768 (KVA space 3G)? Have some other
> > options to be tuned besides KVA_PAGES?
>
> IMO, KVA need to be more than half of physical memory.  But I tend
> to use a lot of mbufs and mbuf clusters in products I work on lately
> (mostly networking stuff).  If you don't tune kernel memory usage up,
> then you may be able to get away with 2G.
>
> So: 2G might be OK, 3G would be more certain, given you are cranking
> some things up, in the config you posted, that make me think you will
> be eating more physical memory.

Are you talking primarily about SHMMAXPGS=262144 option here? Then may be
it'll be oevrall better to reduce it and make KVA space 2G, to leave more
room for user address space? You see, there cannot be any much possibility
to make experiments with this server, so I very much relay on your
advices, thank you again.

>
> If you follow the 1.5 rule, then you will have 6G of swap when you
> have 4G of physical RAM, and will definitely need to go for 3G of
> KVA space.
>

No, the swap is very slightly used on this server, and the total swap
size is 2G.

> Note, though: all space you add to KVA is subtracted from the process
> address space, so if you need big processes, sometimes you are better
> off with less physical RAM, and a larger user virtual address space.
>
> For other tuning information, see also "man tuning".


----
Alexander Varshavchick, Metrocom Joint Stock Company
Phone: (812)118-3322, 118-3115(fax)





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