From owner-freebsd-arch Wed Nov 22 10:28: 7 2000 Delivered-To: freebsd-arch@freebsd.org Received: from pike.osd.bsdi.com (pike.osd.bsdi.com [204.216.28.222]) by hub.freebsd.org (Postfix) with ESMTP id 9628837B4C5 for ; Wed, 22 Nov 2000 10:28:03 -0800 (PST) Received: from foo.osd.bsdi.com (root@foo.osd.bsdi.com [204.216.28.137]) by pike.osd.bsdi.com (8.11.0/8.9.3) with ESMTP id eAMIRh041632; Wed, 22 Nov 2000 10:27:43 -0800 (PST) (envelope-from jhb@foo.osd.bsdi.com) Received: (from jhb@localhost) by foo.osd.bsdi.com (8.11.1/8.11.0) id eAMINr255285; Wed, 22 Nov 2000 10:23:53 -0800 (PST) (envelope-from jhb) Message-ID: X-Mailer: XFMail 1.4.0 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <20001121175100.B18037@fw.wintelcom.net> Date: Wed, 22 Nov 2000 10:23:53 -0800 (PST) Organization: BSD, Inc. From: John Baldwin To: Alfred Perlstein Subject: Re: Thread-specific data and KSEs Cc: arch@FreeBSD.ORG, Jonathan Lemon , Daniel Eischen Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 22-Nov-00 Alfred Perlstein wrote: > * John Baldwin [001121 17:19] wrote: >> >> On 22-Nov-00 Daniel Eischen wrote: >> >> %gs ? as I mentioned in my other message, this one might be useful for >> >> addressing a structure of thread-local variables much like %fs is used >> >> for >> >> per-CPU data. It also has value in that supposedly x86-64 (aka k64) has >> >> both >> >> %fs and %gs, but no other seg regs. >> > >> > All I need is one. >> >> Well, %gs would cover x86 and k64. I think ia64 has several application >> registers that are available for OS use and we could steal one of those. >> I'm >> not sure about the alpha though. > > Don't more segment registers cause more overhead for context switches? Hardly. The biggest pain involved in a context switch is the TLB, not 2 (4?) extra mov instructions. :) > Just wondering. -- John Baldwin -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message