Date: Sun, 3 May 1998 21:34:35 +0200 From: Eivind Eklund <eivind@yes.no> To: Nate Williams <nate@mt.sri.com> Cc: John Hay <jhay@mikom.csir.co.za>, freebsd-bugs@FreeBSD.ORG Subject: Re: i386/5398 Message-ID: <19980503213435.36715@follo.net> In-Reply-To: <199805031858.MAA20839@mt.sri.com>; from Nate Williams on Sun, May 03, 1998 at 12:58:27PM -0600 References: <199805031749.TAA07478@zibbi.mikom.csir.co.za> <11869.894218238@critter.freebsd.dk> <199805031858.MAA20839@mt.sri.com>
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On Sun, May 03, 1998 at 12:58:27PM -0600, Nate Williams wrote: >>> 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? >> >> I don't know how it is done exactly, check with XFree86. I just know >> that any PCI bus hogging will send your interrupt latency soaring :-( > > ps. It's not just PCI bus hogging, since I've got an ISA box that also > sees the same thing. As a matter of fact, I'm pretty sure it's > completely unrelated to any particular bus architecture. It isn't. I don't know if any PC-based hardware has a solution for the problem, but a bus design can avoid total busmastering and instead allocate fractions. It would give a slight slowdown when the capability was used (you'd have to abort a bus-run to let other devices have bus access), or it would require parallell bus tech, but it isn't undoable. Basically, it is the hardware parallel of multitasking. Eivind. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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