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Re: Tracing KVM with Systemtap
- From: Rayson Ho <rho at redhat dot com>
- To: Stefan Hajnoczi <stefanha at gmail dot com>
- Cc: kvm at vger dot kernel dot org, systemtap at sources dot redhat dot com, Prerna Saxena <prerna at linux dot vnet dot ibm dot com>
- Date: Tue, 21 Sep 2010 08:58:07 -0400
- Subject: Re: Tracing KVM with Systemtap
- References: <1283952030.2631.19.camel@computer> <AANLkTimbrDwhHOZxWiWhzKQgt=yq6N7GWkGHtJK3sHSR@mail.gmail.com> <1284988762.2500.13.camel@computer> <AANLkTikr3eRT27r9w23_G89oxrMDhtukW4vN9UUhuMwH@mail.gmail.com>
On Mon, 2010-09-20 at 14:36 +0100, Stefan Hajnoczi wrote:
> Right now there are few pre-defined probes ("trace events" in QEMU
> tracing speak). As I develop I try to be mindful of new ones I create
> and whether they would be generally useful. I intend to contribute
> more probes and hope others will too!
I am still looking at/hacking the QEMU code. I have looked at the
following places in the code that I think can be useful to have
statistics gathered:
net.c qemu_deliver_packet(), etc - network statistics
<CPU Arch>/op_helper.c global_cpu_lock(), tlb_fill() - lock & unlock,
and TLB refill statistics
balloon.c, hw/virtio-balloon.c - ballooning information.
Besides the ballooning part, which I know what it is but don't fully
understand how it works, the other parts can be implemented as Systemtap
tapsets (~ "DTrace scripts") in the initial stage.
I will see what other probes are useful for the end users. Also, are
there developer documentations for KVM? (I googled but found a lot of
presentations about KVM but not a lot of info about the internals.)
Rayson
>
> Prerna is also looking at adding useful probes.
>
> Stefan