From owner-freebsd-hackers  Thu Aug 12 22:41: 5 1999
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	Fri, 13 Aug 1999 00:41:07 -0700
Date: Fri, 13 Aug 1999 00:41:07 -0700
From: Arun Sharma <adsharma@home.com>
To: Mark Newton <newton@internode.com.au>
Cc: freebsd-hackers@FreeBSD.ORG
Subject: Re: mmap bug
Message-ID: <19990813004107.A17205@home.com>
References: <19990812235208.A17058@home.com> <199908130534.PAA25953@gizmo.internode.com.au>
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In-Reply-To: <199908130534.PAA25953@gizmo.internode.com.au>; from Mark Newton on Fri, Aug 13, 1999 at 03:04:43PM +0930
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On Fri, Aug 13, 1999 at 03:04:43PM +0930, Mark Newton wrote:
> Arun Sharma wrote:
> 
>  > The second alternative - to mark system daemons as special
>  > sounds much more attractive.
> 
> Ok, now define the difference between "system daemons" and any other
> daemon (or, for that matter, any other process).

That's easy. 

$ ps aux | head
USER       PID %CPU %MEM   VSZ  RSS  TT  STAT STARTED      TIME COMMAND
root     23924  5.0 30.2 41312 38716  ??  S    Sat05PM 191:41.92 /usr/X11R6/bin/
root         0  0.0  0.0     0    0  ??  DLs  31Jul99   0:02.30  (swapper)
root         1  0.0  0.2   504  200  ??  ILs  31Jul99   0:00.05 /sbin/init --
root         2  0.0  0.0     0    0  ??  DL   31Jul99   0:03.18  (pagedaemon)
root         3  0.0  0.0     0    0  ??  DL   31Jul99   0:00.00  (vmdaemon)
root         4  0.0  0.0     0    0  ??  DL   31Jul99   0:03.55  (bufdaemon)
root         5  0.0  0.0     0    0  ??  DL   31Jul99  12:06.17  (syncer) 

The daemons which are involved in freeing up pages during low memory
conditions qualify as system daemons. Making sure that these daemons
don't block avoids the deadlock.

	-Arun



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