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Date:      Tue, 20 Mar 2001 10:31:30 -0800
From:      Alfred Perlstein <bright@wintelcom.net>
To:        "Michael C . Wu" <keichii@peorth.iteration.net>
Cc:        Matt Dillon <dillon@earth.backplane.com>, "Michael C . Wu" <keichii@iteration.net>, izero@ms26.hinet.net, cross@math.psu.edu, grog@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG
Subject:   Re: tuning a VERY heavily (30.0) loaded scerver
Message-ID:  <20010320103130.Y29888@fw.wintelcom.net>
In-Reply-To: <20010320122350.F52586@peorth.iteration.net>; from keichii@iteration.net on Tue, Mar 20, 2001 at 12:23:50PM -0600
References:  <20010320111144.A51924@peorth.iteration.net> <20010320092717.R29888@fw.wintelcom.net> <20010320113818.B52586@peorth.iteration.net> <20010320120112.C52586@peorth.iteration.net> <200103201815.f2KIFR594803@earth.backplane.com> <20010320122350.F52586@peorth.iteration.net>

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* Michael C . Wu <keichii@iteration.net> [010320 10:27] wrote:
> On Tue, Mar 20, 2001 at 10:15:27AM -0800, Matt Dillon scribbled:
> | 
> | :Another problem is that we have around 4000+ processes accessing
> | :lots of SHM at the same time..
> | 
> |     How big is 'lots'?  If the shared memory segment is smallish, e.g.
> |     less then 64MB, you should be ok.  If it is larger then you will
> |     have to do some kernel tuning to avoid running out of pmap entries.
> 
> This is exactly what happens to us sometimes. We run out of pmap entries. :)
> But what can we tune?

If this is a result of the shared memory, then my sysctl should fix it.

Be aware, that it doesn't fix it on the fly!  You must drop and recreate
the shared memory segments.

better to reboot actually and set the variable before any shm is
allocated.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]


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