Hi Mark-Jan, Thanks for your response.
On 03/05/2019 00:02, Mark-Jan Bastian wrote: > For more in-depth USB debugging, there are external USB 2.0 and 3.x > hardware bus analysers available, for example from the swiss company > ellisys.com. I have experience in USB protocol analysis from a previous job, and know the Ellisys tools among others. As a consequence, I have an idea about what effort it implies to look at the problem from that angle (one could call this a "bottom-up approach"), and I won't go that way. > Some things can be very subtle, for example this (quite amazing) > 2013 ethernet PHY bug: > https://www.theregister.co.uk/2013/02/06/packet_of_death_intel_ethernet/ > Very tough engineering by the affacted customer, who made it reproducable > and fixed by a simple EEprom update from the vendor. Interesting story, but I hope it is not a parallel to my situation, and that a simpler approach will fix it. > Pure theory: What if this intermittent issue would be an issue with a > certain sequence of packetlengths, some of them on the boundary of the > maximum size for that endpoint and endpointtype, that are not handled > properly at one or both sides, causing a glitch/retransmission/faillure, > resulting in the application-level visible underruns ? > How would you measure that ? How could you optimize the packetlengths > so that the issue is quicker to reproduce ? Or avoid the issue by > anticipating and avoiding such packetsequences ? It's a possible hypothesis, but I don't see how to test it easily. >> Could CPU frequency scaling lead to interruptions? > > It would leave that off [...] I'd love to, but it's not clear to me how to achieve that nowadays with the intel_pstate driver: https://www.kernel.org/doc/html/v4.12/admin-guide/pm/intel_pstate.html It's probably not even possible anymore given that the cpu and voltage scaling responsiblity got moved into the processor itself. mpb _______________________________________________ USRP-users mailing list [email protected] http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
