From owner-cvs-all  Sun Jun 24 11:58:45 2001
Delivered-To: cvs-all@freebsd.org
Received: from sneakerz.org (sneakerz.org [216.33.66.254])
	by hub.freebsd.org (Postfix) with ESMTP
	id 186E737B401; Sun, 24 Jun 2001 11:58:39 -0700 (PDT)
	(envelope-from bright@sneakerz.org)
Received: by sneakerz.org (Postfix, from userid 1092)
	id 60E365D010; Sun, 24 Jun 2001 13:58:28 -0500 (CDT)
Date: Sun, 24 Jun 2001 13:58:28 -0500
From: "Jonathan Lemon <jlemon@flugsvamp.com>    Alfred Perlstein" <bright@sneakerz.org>
To: Mike Silbersack <silby@silby.com>
Cc: Matt Dillon <dillon@earth.backplane.com>,
	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
Message-ID: <20010624135828.A64836@sneakerz.org>
References: <200106231730.f5NHUNd73058@earth.backplane.com> <20010623131152.I23528-100000@achilles.silby.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2i
In-Reply-To: <20010623131152.I23528-100000@achilles.silby.com>; from silby@silby.com on Sat, Jun 23, 2001 at 01:14:11PM -0500
Sender: owner-cvs-all@FreeBSD.ORG
Precedence: bulk
List-ID: <cvs-all.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo?subject=subscribe%20cvs-all>
List-Unsubscribe: <mailto:majordomo?subject=unsubscribe%20cvs-all>
X-Loop: FreeBSD.ORG

* Mike Silbersack <silby@silby.com> [010623 13:14] wrote:
> 
> 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.

bzero seems to be optimized for large areas, perhaps it would help
malloc some if we used some alternative zero'ing function for small
allocations with M_ZERO set?

-Alfred

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message