Date: Thu, 18 Jan 2001 07:23:02 +1100 From: Peter Jeremy <peter.jeremy@alcatel.com.au> To: John Baldwin <jhb@FreeBSD.ORG> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, current@FreeBSD.ORG, Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, Robert Drehmel <robert@gizmo.quizbot.org> Subject: Re: Atomic breakage? Message-ID: <20010118072302.E98607@gsmx07.alcatel.com.au> In-Reply-To: <XFMail.010117102803.jhb@FreeBSD.org>; from jhb@FreeBSD.ORG on Wed, Jan 17, 2001 at 10:28:03AM -0800 References: <53512.979753444@critter> <XFMail.010117102803.jhb@FreeBSD.org>
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On 2001-Jan-17 10:28:03 -0800, John Baldwin <jhb@FreeBSD.ORG> wrote: > So as long as we keep all >atomically-accessed 64-bit integers within a single page we should be fine for >CX8 on all pentiums should we even want 64-bit atomic ops. This comes free of charge (along with better performance) if all 64-bit objects are aligned on 8-byte boundaries. By default our gcc only enforces long (4-byte) alignment (apparently, this is part of the IA32 ABI). We can get 8-byte alignment by adding "__attribute__((aligned(8)))" to the object definition. This is one area where I think we would be better off changing our gcc to default to aligning "long long" (and maybe "double") at 8-byte boundaries. We should at least have an alignment expansion in <sys/cdefs.h> Peter To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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