Charles- >> I would tend to blame Linux and buffering more than GbE itself (MAC + PHY). >> Here is an interesting doc where the >> researchers were asking similar questions: >> >> http://www.hep.man.ac.uk/u/rich/atlas/docs/atlas_net_note_draft5.pdf >> >> I'm not sure yet how much buffering is done in the USRP2 firmware but we >> hope to know shortly as a couple of our >> guys >> are in the process of taking apart the logic, pulling out non-GbE related >> sections, and rebuilding. >> >> -Jeff > > I glanced over the document briefly and was wondering if your analysis > of the linux issue was because of this document, or a separate source. > I'm only asking because the document is 10 years old and is using > RedHat 5 and Pentium 2s. I would assume the linux kernel support for > GigE has improved since then.
Which part of the Linux issue... sustained throughput or latency? I wouldn't be surprised to find that latency hasn't improved substantially because it's not a priority for server software. Even VoIP applications are not concerned about a 1 msec improvement... whereas that makes or breaks a wireless MAC. What I found interesting in that particular document is the authors were careful not to speculate and to use a logic analyzer to make exact measurements. For me the key figures are GbE (MAC + PHY) and PCI latencies, which are likely not too reducible. -Jeff _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio