From owner-cvs-all  Sat Jun 23 11:14:15 2001
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Date: Sat, 23 Jun 2001 13:14:11 -0500 (CDT)
From: Mike Silbersack <silby@silby.com>
To: Matt Dillon <dillon@earth.backplane.com>
Cc: "Jonathan Lemon <jlemon@flugsvamp.com>    Alfred Perlstein" <bright@sneakerz.org>,
	Mike Silbersack <silby@FreeBSD.ORG>, <cvs-committers@FreeBSD.ORG>,
	<cvs-all@FreeBSD.ORG>, <jlemon@FreeBSD.ORG>, <bmilekic@FreeBSD.ORG>
Subject: Re: cvs commit: src/sys/netinet tcp_input.c tcp_output.c tcp_subr.c
 tcp_timer.c tcp_usrreq.c tcp_var.h
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On Sat, 23 Jun 2001, Matt Dillon wrote:

>     Yes, there's no question bzero() should be removed.  The subroutine
>     overhead alone, never mind it doing anything, is enough to blow away
>     any benefit.  Hence:
>
>     Test3 - man load w/ptrs          35.73 nS/loop
>     Test4 - mlptrs & bzero          161.60 nS/loop
>
>     Ouch!  Of course, us old timers also see the fact that the entire
>     subroutine runs dozens of instructions in less then a microsecond and
>     say "ooooh, cool...".
>
> 						-Matt

Wow!  Thanks for the optimization, I hadn't considered that bzero could be
so slow.

I'm about to take off right now, I'll see if I can mock up some benchmarks
of the overall performance of tcp_output when I get back on Monday.

Mike "Silby" Silbersack


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