>On Wed, 2002-05-22 at 21:48, [EMAIL PROTECTED] wrote: >> >What about a mixed approach to avoid unnecessary bus traffic: try to read >> >the ring head pointer from memory, and if after a timeout the free >ring space >> >still doesn't seem to be large enough, read it directly from the register. >> >This could hurt performance badly if the memory copy is often outdated >> though. >> >> Well, let's first make it stable... > >Good idea. :) Do you agree with Albert's analysis? Have you tried with >caching enabled yet?
Albert analysis makes sense, though I tried a different approach which was to set the Guarded bit on the BAT mapping. Well, anyway, I'll do some experiments with that again when I have less pressure from work, I can at least try to find some more infos about what's going on in the card when the CCE stops. > >> >> >If apps would at least avoid reading stuff written >> >> >by the video card, write-through cached would be OK. >> >> >Apps that read AGP memory are uncommon enough that >> >> >fixing all of them would be feasible. >> >> >> >> I think we can use full caching (copyback) without too much >> >> problems. In the r128 case, we'll have to flush from the X server >> >> as it's directly writing to the ring (and maybe from the mesa driver >> >> as well). On radeon, it's all done via indirect buffers and those >> >> get passed to the kernel driver before beeing inserted in the ring. >> > >> >Where is r128 different than radeon in this respect? >> >> The last time I looked at r128, it wrote to the ring directly iirc, >> while radeon on wrote to indirect buffers, the kernel putting them >> in the ring. This may have changed though. > >I'm pretty sure only the kernel ever had access to the ring in both >drivers (the only exception I know of were the ati-5-0-[01] branches in >DRI CVS, but they were never merged into the trunk, let alone an XFree86 >release). Ok, my memory may be failing here ;) Ben. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
