Am Mittwoch, den 12.01.2005, 17:34 -0800 schrieb Mark Cass: > felix, > > is there a noticable performance difference with DMA versus the > non-dma version of the savage driver?
It depends on the application. I've noticed a big performance improvement with Torcs for example. The main reason is probably that you can get many more indexed drawing commands (using vertex DMA) onto the command queue than drawing commands with inline vertices. This way parallelism between CPU and GPU can be exploited more effectively. > i have concluded that the DMA driver work can only be compiled and > used with the linux 2.6 kernel, is this true? Yes, this is correct. If you really need this to work on a 2.4 kernel then you could try to backport it to the old DRM. > I ask becuase i am stuck back on the 2.4 kernel. I also believe you > mentioned that it will not work for savage 4 and twister (based on > savage 4) chipsets. what is the time frame for the savage 4/ twister > DMA support? Vertex DMA is working with Savage4-based cards. However, it doesn't work for all vertex formats. The current driver can use DMA for almost everything by choosing an appropriate vertex format, but it can't be used with multi-texturing in most cases. I'm going to implement command DMA for Savage4-based cards at some point. I expect this to have about the same effect as vertex DMA WRT parallelism between CPU and GPU. > if it is true that kernel 2.4 is not supported, how difficult would > it be for me make the DMA stuff work in the old driver? what would be > a good sample driver to work form? If you want a DRM driver that works with the current Mesa driver you need something that has the same binary interface. The only way is to take the Savage DRM driver from linux-core/shared-core and backport it to the old linux/shared DRM. Other drivers that exist both in the old and new DRM might give you a hint what needs to be done. There is also a small bit in the DRM core that would have to be backported to the old DRM, nameley the _DRM_CONSISTENT map type. This is needed for mapping the shadow status page in the Xserver. > > mark -- | Felix Kühling <[EMAIL PROTECTED]> http://fxk.de.vu | | PGP Fingerprint: 6A3C 9566 5B30 DDED 73C3 B152 151C 5CC1 D888 E595 | ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
