From owner-freebsd-arch  Sat Feb 16 14: 3:36 2002
Delivered-To: freebsd-arch@freebsd.org
Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2])
	by hub.freebsd.org (Postfix) with ESMTP
	id C316437B405; Sat, 16 Feb 2002 14:03:33 -0800 (PST)
Received: (from dillon@localhost)
	by apollo.backplane.com (8.11.6/8.9.1) id g1GM3Vu39770;
	Sat, 16 Feb 2002 14:03:31 -0800 (PST)
	(envelope-from dillon)
Date: Sat, 16 Feb 2002 14:03:31 -0800 (PST)
From: Matthew Dillon <dillon@apollo.backplane.com>
Message-Id: <200202162203.g1GM3Vu39770@apollo.backplane.com>
To: Alfred Perlstein <bright@mu.org>
Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, arch@FreeBSD.ORG,
	jhb@FreeBSD.ORG, peter@wemm.org, jake@locore.ca
Subject: Re: gettimeofday() and crhold()/crfree() (was Re: gettimeofday() and copyout(). Is copyout() MPSAFE on non-i386 archs? )
References: <6988.1013844797@critter.freebsd.dk> <200202162033.g1GKXOf13029@apollo.backplane.com> <20020216214709.GA12136@elvis.mu.org>
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-arch.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-arch>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-arch>
X-Loop: FreeBSD.ORG

   This is interesting:

   SHELL1> ./tg &
   SHELL1> ./tg &
   ... 255000 gettimeofday calls per second each

   SHELL1> ./tg
   SHELL2> ./tg
   ... 322000 gettimeofday calls per second each

   I think this is due to the same ucred being shared from the two ./tg 
   runs from the same shell, indication further mutex contention above
   and beyond whatever contention was occuring before with separate instances
   of the ucred (due to sshd setuid'ing and such when starting a new shell).

   I'm not proposing any changes, this is just another data point that we
   may want to keep in mind.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>

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