RE: [ntdev] VBEMP: Fast accelerated DrvBitBltI’m a bit rusty on this, but my experience is that Bitblt is usually fast unless you implement Rops in software. My experience is also that intra-board blits are way, way faster than memory-to-board or board-to-memory blits.
I don’t believe storing the framebuffer in system memory is a good idea either. The way to get performance out of video hardware is to achieve synergy with its design - you write your software for the card, not for the OS. And on the same bus and the same OS, every card is different.
I would put a logic analyzer in that memory interface and see in detail what’s really happening. I might also try to run the board on a VMetro and poke around the bus interface, again, at hw level. Alternatively, I would implement the blit as two texture-mapped triangles to see if I can get any insight on where performance is being lost. But still, I find hardware level debugging an invaluable help in this kind of situation!
Hope this helps,
Alberto.
----- Original Message -----
From: Tim Green
To: Windows System Software Devs Interest List
Sent: Wednesday, September 26, 2007 1:07 AM
Subject: RE: [ntdev] VBEMP: Fast accelerated DrvBitBlt
Or may be store framebuffer in *system*memory (instead of VRAM). and blit from there to *video*memory ?
Yes, that will be much faster than reading the video card’s RAM, especially for cards on buses designed to write data to the card much faster than read from it.
Good luck!
Tim Green
http://www.displaylink.com/
NTDEV is sponsored by OSR
For our schedule of WDF, WDM, debugging and other seminars visit:
http://www.osr.com/seminars
To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer