From owner-freebsd-arch Mon Jun 24 13:59:50 2002 Delivered-To: freebsd-arch@freebsd.org Received: from rover.village.org (rover.bsdimp.com [204.144.255.66]) by hub.freebsd.org (Postfix) with ESMTP id 722F137B434 for ; Mon, 24 Jun 2002 13:58:12 -0700 (PDT) Received: from harmony.village.org (harmony.village.org [10.0.0.6]) by rover.village.org (8.11.3/8.11.3) with ESMTP id g5OKwBY77976; Mon, 24 Jun 2002 14:58:11 -0600 (MDT) (envelope-from imp@village.org) Received: from localhost (warner@rover2.village.org [10.0.0.1]) by harmony.village.org (8.11.6/8.11.6) with ESMTP id g5OKwAG53534; Mon, 24 Jun 2002 14:58:10 -0600 (MDT) (envelope-from imp@village.org) Date: Mon, 24 Jun 2002 14:57:59 -0600 (MDT) Message-Id: <20020624.145759.95908168.imp@village.org> To: winter@jurai.net Cc: phk@critter.freebsd.dk, arch@FreeBSD.ORG Subject: Re: It is time to admit that removable devices exist From: "M. Warner Losh" In-Reply-To: <20020624164822.H95270-100000@sasami.jurai.net> References: <83073.1024951336@critter.freebsd.dk> <20020624164822.H95270-100000@sasami.jurai.net> X-Mailer: Mew version 2.1 on Emacs 21.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message: <20020624164822.H95270-100000@sasami.jurai.net> "Matthew N. Dodd" writes: : I want to see the performance hit this causes quantified on lower end : hardware before drivers are patched to support this API (which I concede : may have some use outside PCMCIA devices.) The cost on low end machines (where you have nexus -> isa -> device) is going to be 3 indirect function calls per call for the non pccard case, which is << 1us cycle time of the ISA bus. 3 indirect function calls would be on the order of 25-100 cycles depending on the CPU. For all but the slowest of hardware no one will notice this extra processing. Even on a 33MHz 386 this would be only about 3us. I doubt I could measure its effect on anything faster than a P90 or P100. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message