Messages in this thread | | | Date | Tue, 24 Jul 2012 11:02:04 +0100 | Subject | Re: [RFC PATCH 0/6] virtio-trace: Support virtio-trace | From | Stefan Hajnoczi <> |
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On Tue, Jul 24, 2012 at 3:36 AM, Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> wrote: > The performance of each method is compared as follows: > [1] Native > - only recording trace data to ring-buffer on a guest > [2] Virtio-trace > - running a trace agent on a guest > - a reader on a host opens FIFO using cat command > [3] IVRing > - A SystemTap script in a guest records trace data to IVRing. > -- probe points are same as ftrace. > [4] Virtio-serial(normal) > - A reader(using cat) on a guest output trace data to a host using > standard output via virtio-serial.
The first time I read this I thought you are adding a new virtio-trace device. But it looks like this series really add splice support to virtio-console and that yields a big performance improvement when sending trace_pipe_raw.
Guest ftrace is useful and I like this. Have you thought about controlling ftrace from the host? Perhaps a command could be added to the QEMU guest agent which basically invokes trace-cmd/perf.
Are you using text formatted ftrace?
Stefan
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