Date: Wed, 22 Nov 2000 10:27:38 -0800 (PST) From: John Baldwin <jhb@FreeBSD.ORG> To: Alfred Perlstein <bright@wintelcom.net> Cc: arch@FreeBSD.ORG, Jonathan Lemon <jlemon@flugsvamp.com>, Daniel Eischen <eischen@vigrid.com> Subject: Re: Thread-specific data and KSEs Message-ID: <XFMail.001122102738.jhb@FreeBSD.org> In-Reply-To: <20001121192331.E18037@fw.wintelcom.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On 22-Nov-00 Alfred Perlstein wrote: > * Daniel Eischen <eischen@vigrid.com> [001121 19:15] wrote: >> > >> > Don't more segment registers cause more overhead for context switches? >> >> It's just one more register that has to be saved. I don't >> think it's going to matter much. > > No extra TLB faults/invalidations? Aren't segment registers > somewhat expensive to load? Not really. The TLB stuff happens when you change %cr3. Also, if you look in cpu_switch, we already save and restore %gs. :) (Which means it may already be used. :( ) Some extra overhead may come from changing the ldt, although if you stick USER_LDT in your kernel you already do that anyways. -- John Baldwin <jhb@FreeBSD.org> -- 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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.001122102738.jhb>