From owner-cvs-all  Fri Aug 16  7: 6:38 2002
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Date: Sat, 17 Aug 2002 00:13:23 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc: David Greenman-Lawrence <dg@dglawrence.com>,
	Alfred Perlstein <bright@mu.org>, <cvs-committers@FreeBSD.org>,
	<cvs-all@FreeBSD.org>
Subject: Re: cvs commit: src/sys/kern uipc_socket2.c 
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On Fri, 16 Aug 2002, Poul-Henning Kamp wrote:

> In message <20020815223211.F42978@nexus.root.com>, David Greenman-Lawrence writ
> >   Calcru() is a tough critter - it would be real nice if Bruce (or anyone)
> >could give me some thoughts on that.

See another reply.

> We may have arrived at the point where it is cheaper to timestamp at all
> boundary conditions instead of doing statistical redistribution.

Not unless a very raw timestamp method were used.  Using nanotime()
would add a 10(?)% overhead to some syscalls even if the hardware part
took no time.  Something using rdtsc() in syscall() might be fast enough,
but this would give similar problems for scaling of very large counts
(cycle counts instead of tick counts).  (nanotime() avoids these problems
by scaling delta-counts, but that is inefficient if it is called often.)

Bruce


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