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Date:      Mon, 28 Aug 1995 13:36:26 -0700 (PDT)
From:      Frank Mayhar <frank@exit.com>
To:        hackers@freefall.FreeBSD.org
Subject:   16-bit pids?  (was Re: 16, 32, and 64bit types?)
Message-ID:  <199508282036.NAA04576@exit.com>
In-Reply-To: <199508282001.GAA12132@godzilla.zeta.org.au> from "Bruce Evans" at Aug 29, 95 06:01:16 am

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Just an aside, not directly related to the original subject.

> Type		FreeBSD		NetBSDr1994/12)	Right
> ----		-------		---------------	-----
> min_pid_t	-		-		u16_t (for PID_MAX = 30000)
> kernel_pid_t	-		-		kernel_promote(min_pid_t)
> pid_t		long		int32_t		user_promote(min_pid_t)

Sixteen bits for PID_MAX?  Yukko!  IMHO, this should be at least 32, and
preferably a black-box type (handled by allocate_pid(), not by an int
increment, as fast that that might be -- it's still one of the least
critical bits of fork()).  Some distributed systems need at least 32
bits for the pid, since they add node information, and a black-box type
would make this much easier.

Granted, it's a nontrivial change, but it would be nice to see some system
do it right.  I don't think there's any inherent reason why pid_t should
be limited to an int (of any size) in modern Un*ces.
-- 
Frank Mayhar frank@exit.com



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