From mboxrd@z Thu Jan 1 00:00:00 1970 Mime-Version: 1.0 (Apple Message framework v749.3) In-Reply-To: References: Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <551EA1F6-28BF-4F57-99B0-3E6A6EEFC659@telus.net> Content-Transfer-Encoding: 7bit From: Paul Lalonde Subject: Re: [9fans] nvidia scrolling performance Date: Sun, 30 Apr 2006 18:00:16 -0700 To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Topicbox-Message-UUID: 4b7d204c-ead1-11e9-9d60-3106f5b1d025 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 8G/s? Nowhere near enough. Enough for text, but try doing real computation using that GPU... PS3 is running 25G/s bi-directional. Those bits move. Paul On 30-Apr-06, at 5:52 PM, erik quanstrom wrote: > i only have a pci card, but someone with an agp card and a machine > that > allows bios-controlled agp bandwidth could eliminate some > possibilities. > if it's bus limited, then the total performance should be linear in > agp > bus speed, right? of course we still wouldn't know which direction on > the bus was limiting. > > perhaps it's time to add another machine to the second-hand > hardware collection. > ;-) > > pci-x (1.066G/s) has the same bandwidth as PCIe x4 (1G/s). > PCIe SLI = 2 * 16x = 8G/s, which ought to be enough for just about > anyone. > > - erik > > On Sun Apr 30 13:13:21 CDT 2006, steve@quintile.net wrote: >>> Frame buffer memory is very very slow to read from, >>> and not just on nvidia. When I did some timings six years >>> ago, I found that reading from frame buffer memory >>> was slower than reading from disk. I'm sure the situation >>> hasn't gotten better. It's not on the fast path for any >>> other system, so the vendors just don't care. >> >> I may be talking rubbish but I understood this is a fundamental >> problem with reading VGA memory over the PCI bus. VGA cards are >> designed for fast writes and not fast reads. >> >> People have been very interested in using the GCPUs in graphics cards >> to do video processing (to disk rather than for display) but the >> limiting >> factor seems to have been the speed at which data can be read back. >> I do hear that some cards are appearing with dual PCIX which will >> allow >> symetric access speeds to the frame buffer. >> >> -Steve >> -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (Darwin) iD8DBQFEVV2gpJeHo/Fbu1wRAowpAJ0SaqAQvQO7LWvyWvbDkAsa9FY6lACgyZaL A9qxHIBefBlanunFaLXl9Nc= =PktC -----END PGP SIGNATURE-----