Date: Mon, 12 Jul 1999 21:21:41 +1000 From: Bruce Evans <bde@zeta.org.au> To: dfr@nlsystems.com, peter@netplex.com.au Cc: freebsd-current@FreeBSD.ORG, jeremyp@gsmx07.alcatel.com.au, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") Message-ID: <199907121121.VAA05708@godzilla.zeta.org.au>
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>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
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