Date: Tue, 11 Feb 2003 15:40:58 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Marco Beishuizen <marco@beishuizen.info> Cc: FreeBSD alpha mailing list <alpha@FreeBSD.ORG> Subject: Re: Why is XFree86 on FreeBSD/Alpha much slower? Message-ID: <15945.24538.794799.926276@grasshopper.cs.duke.edu> In-Reply-To: <Pine.BSF.4.53.0302112129370.294@tsunami.bsd> References: <Pine.BSF.4.53.0302112042190.294@tsunami.bsd> <15945.23721.759825.313603@grasshopper.cs.duke.edu> <Pine.BSF.4.53.0302112129370.294@tsunami.bsd>
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Marco Beishuizen writes:
> On Tue, 11 Feb 2003, the wise Andrew Gallatin spoke, and said:
>
> >
> > Marco Beishuizen writes:
> > >
> > > Hi,
> > >
> > > I have two machines, one Intel (450mhz) and one Alpha (600mhz). Both are
> > > running FreeBSD 4.7-RELEASE and WindowMaker as windowmanager. The Intel
> > > has a Matrox G400max and the Alpha has a Matrox G450.
> >
> > What kind of alpha? What sort of slot is graphics board in on the
> > alpha? On the pc?
> >
> > Drew
>
> The alpha is a PWS600au, it has a 21164 cpu. The Matrox sits in one 32
> bits PCI slot. The Intel is a PIII/450, and the G400 sits in the AGP slot.
>
OK, so the AGP slot probably has at least 500MB/sec DMA.
But: All 32-bit slots on your alpha sit behind a pci-pci bridge chip,
connecting to a main bus whose DMA characteristics are similar to:
DMA rate for 8192 Byte pages (32bit / 33MHz bus)
Timing 32 pages.
bus_read (send) = 73 MBytes/s
bus_write (recv) = 129 MBytes/s
The PCI-PCI bridge slows this down even further. You might try
setting the magic SRM console variable to allow putting the card
into the 64-bit slot (see the alpha hardware notes that Wilo
maintains). But it will still suck moderatly.
FWIW, the AGP Permedia board in my UP1000 doesn't suck.
Drew
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