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Re: [Qemu-devel] Qemu Trace
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] Qemu Trace |
Date: |
Mon, 5 Feb 2018 15:51:08 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Fri, Feb 02, 2018 at 03:53:45PM +0000, Peter Maydell wrote:
> On 2 February 2018 at 10:08, Stefan Hajnoczi <address@hidden> wrote:
> > On Thu, Feb 01, 2018 at 04:30:10PM +0100, Nesrine Zouari wrote:
> >> I am a computer engineering student and I am actually working on my
> >> graduation project at Lauterbach company. The project is about Qemu Trace
> >> and as a future I would like to contribute this work to the main line.
> >>
> >> My project is divided into two parts:
> >>
> >> 1/ Collecting the Guest trace data : The trace solution should be able to
> >> provide:
> >>
> >> a/ Instruction flow Trace
> >>
> >> b/ Memory read/write access
> >>
> >> c/ Time Stamps.
> >>
> >> d/ For tracing rich operating systems that are using MMU, we
> >> additionally need to trace the task switches.
> >
> > Lluìs has done the most instrumentation work in qemu.git and can explain
> > the current status.
>
> I think at the moment the status is that we're still discussing
> what the trace plugin API should be... there are some mailing
s/trace plugin API/instrumentation plugin API/
> list threads on the subject from I think last year some time.
The point of the instrumentation plugin API is for online analysis
(stuff that cannot be post-processed offline) with the ability for the
plugin to control QEMU (e.g. affect translation during a run). That is
not necessary for Nesrine's use case.
I see two main requirements in Nesrine's use case:
1. Instruction flow, memory access, and task switch trace. This doesn't
exist today and requires adding new trace events.
2. An external interface for processing traces. There seems to be a
requirement for doing it online and not by post-processing trace files.
Therefore I suggested looking into LTTng UST, which has an efficient
interface and libraries for tracing processes. I think no QEMU changes
are necessary here.
Stefan
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Re: [Qemu-devel] Qemu Trace, Nesrine Zouari, 2018/02/02