From owner-freebsd-bugs Sun May 3 10:52:25 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA27111 for freebsd-bugs-outgoing; Sun, 3 May 1998 10:52:25 -0700 (PDT) (envelope-from owner-freebsd-bugs@FreeBSD.ORG) Received: from zibbi.mikom.csir.co.za (zibbi.mikom.csir.co.za [146.64.24.58]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id KAA27104 for ; Sun, 3 May 1998 10:52:21 -0700 (PDT) (envelope-from jhay@zibbi.mikom.csir.co.za) Received: (from jhay@localhost) by zibbi.mikom.csir.co.za (8.9.0.Beta5/8.9.0.Beta5) id TAA07478; Sun, 3 May 1998 19:49:22 +0200 (SAT) From: John Hay Message-Id: <199805031749.TAA07478@zibbi.mikom.csir.co.za> Subject: Re: i386/5398 In-Reply-To: <11689.894214766@critter.freebsd.dk> from Poul-Henning Kamp at "May 3, 98 06:59:26 pm" To: phk@critter.freebsd.dk (Poul-Henning Kamp) Date: Sun, 3 May 1998 19:49:22 +0200 (SAT) Cc: freebsd-bugs@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL32 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-bugs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > How is XFree86, a userland program, able to disable interrupts ? > > The Hardware blitter/PCI latency also seems impossible, 115200 = > > 11.5 KBytes/sec = 86uS per character x the FIFO depth (after the hack) > > of 4 or 8 character times is over 500uS. It just doesn't make any > > sense. > > By monopolizing the PCI bus, while blitting 3 or 4 MB data, I can > certainly see PCI starvation. Remeber that to blt 3 MB around, you > have to read 3 MB and write 3MB, so that is 6MB over a 133MB/sec bus, > giving a minimum duration of 45 msec per blt. Just to get my understanding of the hardware a little better. Is this blitting just doing something like a software memory copy, like what the C function bcopy() does? And can that really block interrupts just because it is done over the PCI bus? Or does blitting use something different? John -- John Hay -- John.Hay@mikom.csir.co.za To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message