From: Bakul Shah <bakul+plan9@bitblocks.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] APE fork()
Date: Sat, 12 Aug 2006 11:57:04 -0700 [thread overview]
Message-ID: <20060812185704.4F47929499@mail.bitblocks.com> (raw)
In-Reply-To: Your message of "Sat, 12 Aug 2006 12:54:08 CDT." <266517bde8dfa4628a4a566b35f304be@quanstro.net>
> actually, vfork was implemted (as i understand it) due to insufficient core.
IIRC, it was invented for csh. Typically a shell forks and
then immediately execs a program so all that copying done by
fork was a total waste of time (even setting up copy-on-write
is a waste). vfork avoided copying almost entirely. csh
wouldn't diddle with the parent's memory so *for that one
application* the vfork hack was safe. Of course, we can't
have a special syscall just for one program, can we and
people used it in other programs, lured by its efficiency but
not always fully understanding it.
> fork used to swap the parent to disk and continue with the child process.
Not necessary unless you are running on a machine with *no*
mapping h/w or with memory just enough for a single process.
> vfork was efficient if the child finished before it's scheduling quanta was
> used up.
It was efficient regardless but dangerous.
next prev parent reply other threads:[~2006-08-12 18:57 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-12 12:15 Sascha Retzki
2006-08-12 12:42 ` Victor Nazarov
2006-08-12 12:40 ` Sascha Retzki
2006-08-12 12:55 ` Charles Forsyth
2006-08-12 13:00 ` Victor Nazarov
2006-08-12 14:44 ` david bulkow
2006-08-12 15:09 ` Sascha Retzki
2006-08-12 15:14 ` Victor Nazarov
2006-08-12 15:15 ` Russ Cox
2006-08-12 15:43 ` Leonardo Valencia
2006-08-12 17:22 ` Brantley Coile
2006-08-12 17:54 ` erik quanstrom
2006-08-12 18:57 ` Bakul Shah [this message]
2006-08-12 19:54 ` Charles Forsyth
2006-08-12 20:07 ` erik quanstrom
2006-08-14 4:04 ` Iruatã Souza
2006-08-14 4:33 ` erik quanstrom
2006-08-14 14:41 ` Ronald G Minnich
2006-08-14 14:48 ` erik quanstrom
2006-08-14 14:56 ` Ronald G Minnich
2006-08-14 15:25 ` erik quanstrom
2006-08-14 14:59 ` Martin Neubauer
2006-08-14 15:33 ` John Floren
2006-08-14 15:57 ` erik quanstrom
2006-08-14 13:48 ` Dave Lukes
2006-08-15 4:19 ` William Josephson
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