With thanks to Cheng Wei, the bug reported by Tomasz on loopback has now been resolved. The reason is that * the RFC4342 window counter algorithm (which uses RTT/4) does not work for RTTs < 4 microseconds with the current resolution of 1 microsecond in the Linux implementation (divide-by-zero); * as a result, the window counter does not change when RTT < 4 usec; * which causes the nofeedback timer to halve the sending rate until reaching s/t_mbi (1 packet in 64 seconds). There were some errors in the analysis document on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/ccid3/ccid3_over_loopback/ (specifically section 3). These have been corrected, and a new version has been uploaded. With regard to the RTT-clamping patch: I have heard no report back from Tomasz, but with the revised analysis I am sure that the bug will disappear when clamping the RTT to values > 4 microseconds. Although therefore clamping at 10 microseconds would be sufficient, I still think that a greater value will be better. After all, the packet scheduling is on the order of milliseconds. Will post patch etc. early next week. Gerrit -- To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
