From owner-freebsd-current Mon Jul 12 4:24:27 1999 Delivered-To: freebsd-current@freebsd.org Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.26.10.9]) by hub.freebsd.org (Postfix) with ESMTP id E07E114C8E for ; Mon, 12 Jul 1999 04:24:23 -0700 (PDT) (envelope-from bde@godzilla.zeta.org.au) Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.7/8.8.7) id VAA05708; Mon, 12 Jul 1999 21:21:41 +1000 Date: Mon, 12 Jul 1999 21:21:41 +1000 From: Bruce Evans Message-Id: <199907121121.VAA05708@godzilla.zeta.org.au> To: dfr@nlsystems.com, peter@netplex.com.au Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") Cc: freebsd-current@FreeBSD.ORG, jeremyp@gsmx07.alcatel.com.au, mike@ducky.net Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >I was under the impression that a locked instruction was essentially free >at runtime, with the sole exception of being one byte larger. No, they are very expensive, at least when done in a minimal loop (8 cycles on my P5/133 UP and 16 cycles on my Celeron/450). ISTR Steve Passe saying that they took 30 cycles on an early SMP system. >Also, with the posted example, atomic_cmpex() is #ifndef I386_CPU - that >means it won't be available on any of the default kernels, either at >install time or for 99% of post-install systems built from a release. No one seems to have noticed dropping of support for coprocessorless/ working-FPU-emulatorless systems in cc (the default for -ffancy-math-387 changed from off to on with egcs). Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message