Date: Fri, 19 May 2000 17:44:27 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: wes@softweyr.com (Wes Peters) Cc: tlambert@primenet.com (Terry Lambert), cp@bsdi.com (Chuck Paterson), dfr@nlsystems.com (Doug Rabson), arch@FreeBSD.ORG Subject: Re: Sparc & api for asynchronous task execution (2) Message-ID: <200005191744.KAA00232@usr02.primenet.com> In-Reply-To: <3924DA18.392990EA@softweyr.com> from "Wes Peters" at May 19, 2000 12:07:20 AM
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> Terry Lambert wrote: > > > > > }I didn't realize that every function call involved a fault on the sparc > > > }architecture - that sounds pretty nasty. > > > > > > Actually every function call doesn't cause a fault, every > > > time you overflow/underflow the current set of register windows causes a > > > fault. (Perhaps what you meant). This means that calling a function > > > from the bottom most function will cause two faults, one for going down > > > and one eventually as you go up. > > > > > > This makes going up and down when you don't overflow > > > very fast at the expense of when you add to the total depth. > > The register window sizes weren't picked willy-nilly. The SPARC default > size is 7 windows, chosen after months of analyzing every M68K SunOS > program they could get their hands, including compiled C, Pascal, LISP, > and Fortran programs. > > I suspect C++ and Java probably skew these stats a little. This might > account for the 8 windows in more modern SPARC processors. Please watch your attributions; I said none of this. The truncated pat that included my comments was merely a reference to the 1991 University of Washington paper on SPARC register windows and user space threading, which has a good discussion of SPARC register windows. PS: Not to give you a hard time, but this stuff is archived, and I am always prepared to defend/acknowledge-incorrectness for everything I say, but not for what others say. 8-). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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