On Sat, 15 Jun 2002, Keith Whitwell wrote: > Linus Torvalds wrote: > > > > On Fri, 14 Jun 2002, José Fonseca wrote: > > > >>So to avoid being constantly checking for conclusion before asking to > >>process new entries we devised a different scheme: > >> > >> - after adding new entries to the ring > >> > >> - toggle the end flag of the previous last entry, so that the engine > >>will also process our just commited buffers > >> > > > > If this is in non-coherent memory (AGP), I hope you do an "sfence" in > > between those two stages? You also need to make sure that the compiler > > hasn't re-ordered them (ie a compiler barrier() in between), regardless of > > memory ordering. > > > > I also hope you do the toggle with a locked cycle so that you don't lose > > any information.. > > Is this necessary if the toggle is really just a write? Jose, you're not > doing a read-modify-write operation on that flag are you?
Actually, with the current implementation it is a read-modify-write. Jose, we could avoid that by caching the ring offset and data for BM_COMMAND from the (previous) tail as my original patch did. > I suppose to some extent we're relying on the atomicity of the mach64's use of > that flag as well -- I don't know if there are any obvious ways they could get > it wrong (I assume they just fetch it once...) -- so that's probably not a > huge problem. > > Keith > > > > > _______________________________________________________________ > > Don't miss the 2002 Sprint PCS Application Developer's Conference > August 25-28 in Las Vegas - >http://devcon.sprintpcs.com/adp/index.cfm?source˙dntextlink > > _______________________________________________ > Dri-devel mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/dri-devel > -- Leif Delgass http://www.retinalburn.net _______________________________________________________________ Don't miss the 2002 Sprint PCS Application Developer's Conference August 25-28 in Las Vegas - http://devcon.sprintpcs.com/adp/index.cfm?source=osdntextlink _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
