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Date:      Wed, 26 Aug 1998 01:55:00 +0000 (GMT)
From:      Terry Lambert <tlambert@primenet.com>
To:        mike@smith.net.au (Mike Smith)
Cc:        michaelh@cet.co.jp, gpalmer@FreeBSD.ORG, chuckr@glue.umd.edu, freebsd-current@FreeBSD.ORG
Subject:   Re: Threads across processors
Message-ID:  <199808260155.SAA00915@usr04.primenet.com>
In-Reply-To: <199808251338.NAA02533@dingo.cdrom.com> from "Mike Smith" at Aug 25, 98 01:38:18 pm

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> > Our pipes are very fast.  SYSV SHM's blunder is that it uses full blown
> > system calls for synchronization.
> 
> Yes.  Anyone that thinks in terms of a context switch per transaction 
> between coprocesses is not designing properly.  Using a shared mmap() 
> region and datastructures that don't require locking is another 
> cost-effective technique.

A dirty little secret is that SYSV SHM in FreeBSD is much faster
than mmap, because pages backed by anonymous pages instead of a
vnode pager object do not have to be written through...


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.

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