On Sun, 2009-02-15 at 11:04 +0100, Ingo Molnar wrote: > It would be nice to enhance this single-CPU trace some more - to more > surgically see what is going on. Firstly, absolute timestamps would be > nice: > > echo funcgraph-abstime > trace_options > echo funcgraph-proc > trace_options > > as it's a bit hard to see the global timescale of events. Okay, here's some more trace data. I grabbed a few samples at different times during the ping test. I think the data in files trace6.txt and trace8.txt coincided with some of the biggest delays. http://disenchant.net/tmp/bug-12465/trace-2/ This is captured on 2.6.29-rc5-tip-02057-gaad11ad. The kvm guest being pinged is process 11211: flexo:~# pstree -p 11211 qemu-system-x86(11211)─┬─{qemu-system-x86}(11212) ├─{qemu-system-x86}(11213) └─{qemu-system-x86}(11609) Cheers, Kevin. > Secondly, not all events are included - in particular i dont really see > the points when packets are passed. Would it be possible to add a tracing > hypercall so that the guest kernel can inject trace events that can be seen > on the native-side trace? Regarding ping latencies really just two things > matter: the loopback network device's rx and tx path. We should trace the > outgoing sequence number and the incoming sequence number of IP packets, > and inject that to the host side. This way we can correlate the delays > precisely. > > Ingo -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
