hi dave, the PPC ethernet bottleneck is in the PPC code needed to read data from the FPGA, format the data, and write it to the ethernet port . if you spend work at optimizing your code, you can get a higher data rate.
dan On Mon, Apr 29, 2013 at 8:35 AM, David MacMahon <[email protected]>wrote: > Hi, Jason, > > Why only a factor of 2 faster instead of a factor of 10? What is the > limiting factor other than ethernet speed? > > 10 Mbps throughput over a 100 Mbps link (10% efficiency) seems not so > great but understandable/acceptable. > > 20 Mbps throughput over a 1,000 Mbps link (2% efficiency) seems kind of > bad. > > Thanks, > Dave > > On Apr 28, 2013, at 11:21 PM, Jason Manley wrote: > > > ROACH2's PHY is different. It's now Marvel (as opposed to a National > Semi on ROACH1). It works reliably at 1Gbps. > > > > I bank on 10Mb/s on ROACH1, which is achievable using the normal katcp > and tcpborphserver2 without any trickery. You can get better if you write > your own PPC code. > > > > ROACH2 should be about a factor of 2 faster, but I haven't benchmarked > it. > > > > Jason > > > > On 29 Apr 2013, at 00:08, John Ford wrote: > > > >>> hi john, > >>> > >>> i think all roach1's PPC ethernet ports need to be used at 100Mb/sec > port > >>> speed, > >>> independent of when the boards were made, and not at 1Gbit/sec. > >>> > >> > >> Thanks, Dan. I thought that a PHY chip had been changed, but I couldn't > >> remember. Now I seem to recall that the Phy is just Not Good. > >> > >>> it's tricky to write PPC software that gets more than 20Mbit/sec > >>> out of the port, but i'm not sure about this 20Mbit/sec number. > >> > >> OK. I wonder if anyone else has experience with this? I guess we'll > test > >> it if not... > >> > >> John > >> > >>> > >>> best wishes, > >>> > >>> dan > >>> > >>> > >>> On Sun, Apr 28, 2013 at 1:57 PM, John Ford <[email protected]> wrote: > >>> > >>>> Hi all. > >>>> > >>>> Can someone tell me if the ethernet port on the newer ROACH boards is > >>>> reliable at 1 gb/s? > >>>> > >>>> Also, what is the maximum data rate expected through that interface? > >>>> > >>>> Thanks! > >>>> > >>>> John > >>>> > >>>> > >>>> > >>>> > >>> > >> > >> > >> > > > > > > >
