Date: Wed, 02 Jan 2002 12:49:37 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: mitko@rila.bg Cc: hackers@freebsd.org Subject: Re: Magic number 100 in /sys/kern/kern_fork.c Message-ID: <3C337261.6BB5BFE0@mindspring.com> References: <20020102134345.2a00458f.mitko@rila.bg>
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Dimitar Peikov wrote:
>
> I've review /sys/kern/kern_fork.c file and have a question why the room of
> 100 process numbers is hardcoded in the source? I think that if such room
> is needed, it must be defined somewhere in headers, isn't it.
>
> Can someone explain me more the idea about that room?
It's a setaside for system processes ("kprocs") at system start;
think of it like the 1024 priviledged port reserve. I think
the idea is to not have a random PID collide with a system process
that was started at init time. If you start a heck of a lot of
processes/kprocs, you will occasionally get collisions, but by not
excluding where you *know* there are processes from the space, you
are pretty much asking for a (very small) slowdown.
The code is pretty straight forward, though a manifest constant
mich be moreso; I don't know how permitting it to be changed
would be of benefit. I could see how someone without scruples
could "hide" processes, if it were runtime adjustable...
-- Terry
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