On a semi-related note, I've notice the CPU running pretty hot when I read data fast from the FPGA and make packets out of it. Do we need heatsinks for the CPU?
On Wed, Apr 28, 2010 at 10:44 PM, Jason Manley <[email protected]> wrote: > ROACH bus runs at 66MHz (or 83MHz if you "overclock" it to boot config H). I > agree that the 3.5MB/s is miserable performance considering what it should > be capable of achieving. I suspect these bottlenecks are mostly BORPH > related. I also recall an extended bus handshake being mentioned for every > bus transaction. Dave G, Marc or Shanly might be able to comment further. I > believe Shanly has been working on some optimisation in BORPH. Dave, what > speeds can you get through uboot? Is there room for optimisation here? I > would also welcome a speedup. > > Jason > > On 28 Apr 2010, at 20:11, David MacMahon wrote: > >> Hi, Mel, >> >> On Apr 28, 2010, at 9:54 , melvyn wright wrote: >> >>>>> You should be getting around 7MegaBytes/s across that bus. >>>> >>>> 56 Mb / 16 b < 4 MHz << bus clock frequency >>> >>> Good suggestion re kernel, but don't understand the significance of the >>> 56 Mb >> >> I omitted the "/s" in "56 Mb/s". 7 megabytes/s == 56 Megabits/s. Since >> the bus to the FPGA is 16 bits wide, dividing by 16 gives the number of 16 >> bit words transferred per second as around 3.5 million. I don't know the >> frequency at which the bus runs, but I suspect it is far greater than 3.5 >> MHz hence my comment about room for improvement. >> >> Dave >> >> P.S. I don't know how conventional or official it is, but I use lowercase >> 'b' for "bit" and uppercase 'B' for "byte". >> >> >> > > > > > > -- Aaron Parsons 510-406-4322 (cell) Campbell Hall 523, UCB
