On Fri, 3 Oct 2003, Paul wrote: > >All of the creator3D support I wrote is 32-bit and takes full advantage > > of the UPA bandwidth. 64-bits or not makes no difference wrt. to this, > > so your ignorance is showing again... The bus bandwidth of UPA > > is 64-bytes in one transfer, not 64-bits. The 64-bit transfers are > > accomplished using the UltraSPARC block load and store instructions > > that move 64-bytes at a time in and out of the floating point registers. > > These instructions are fully available in 32-bit mode. > > Again, you seem to be looking at it sheerly through the software side of > things. The bus bandwidth is not 64 bytes. Bandwidth is a term of velocity: > amount over time. > http://dictionary.reference.com/search?q=bandwidth > "2. The amount of data that can be passed along a communications channel in > a given period of time. " > > So, Bandwidth would have to include the clock speed of the bus AND the data > width. Which happens to be 64 bits. > > http://docs.sun.com/db/doc/805-7764-12/6j7a77hhh?a=view#z400010a55fa > "The UPA 64-bit data bus provides the connection between the CPU module and > the UPA graphics. The 64-bit UPA data shares the data bus with memory > through six transceiver chips."
According to this document (http://www.eecis.udel.edu/nsfri/docs/Ultra-II/UPA.pdf), the UPA *address* bus is 64 bit wide, and its *data* bus is 144 bit wide, with 128 bits for data and 16 bits for error checking. I saw mentions of 64-byte transfer blocks in other documents, for example for the prefetch instruction. Thanks Google for those interesting documents. ;) > Maybe I'm just an old fogey who remembers the days when you tried to wring > out the performance by aligning software as closely to hardware as possible. > Maybe I think it's strange/inelegant to have a nonworking architecture in > the kernel source. What are you talking about? nonworking architecture? -- Erwann ABALEA <[EMAIL PROTECTED]> - RSA PGP Key ID: 0x2D0EABD5 ----- SM> Désolé (c'est quand-même terrible cette société oû l'on doit SM> s'excuser d'être doué, vraiment...) Si en + tu devais t'excuser d'être crétin t'aurais un job a plein temps -+- RM in http://neuneu.ctw.cc - Là, ya indubitablement consensus -+-
