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Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentati
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation |
Date: |
Fri, 28 Jul 2017 15:06:23 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Fri, Jul 28, 2017 at 02:41:19PM +0100, Peter Maydell wrote:
> On 28 July 2017 at 14:34, Stefan Hajnoczi <address@hidden> wrote:
> > Lluís/Peter: What are the requirements for instrumentation code
> > interacting with the running QEMU instance? simpletrace is
> > asynchronous, meaning it does not wait for anyone handle the trace event
> > before continuing execution, and is therefore not suitable for
> > SystemTap-style scripts that can interact with the program while
> > handling a trace event.
>
> I think you'd probably want synchronous -- it's pretty helpful
> to be able to say "register a trace event hook that doesn't
> fire very often, and use that to get to the region of
> execution that's of interest to you, then enable more hooks
> to get more detail at that point". (For instance, "wait til
> we've executed 5,000,000 instructions, then turn on the
> tracing of all instruction execution, register modification
> and memory accesses".)
Currently simpletrace probes have a fixed action when they are enabled,
namely to print state to the trace log file. Perhaps we can make the
action more flexible, if we create a more formal protocol for simpletrace
to let it talk over a UNIX socket. By default it could send probe data
asynchronously as now, but you could mark probes such that they require
a synchronous ACK, thus pausing execution until that ACK is received
from the instrumenting program.
For that to be useful, we would need to have allow probes to be turned
on/off via this trace socket, since the normal HMP/QMP monitor execution
would be blocked while this probe is running.
Regards,
Daniel
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- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, (continued)
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Peter Maydell, 2017/07/26
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/26
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Daniel P. Berrange, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Peter Maydell, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Daniel P. Berrange, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Peter Maydell, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Daniel P. Berrange, 2017/07/27
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Stefan Hajnoczi, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Peter Maydell, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation,
Daniel P. Berrange <=
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Daniel P. Berrange, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/28
- Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/27
Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation, Lluís Vilanova, 2017/07/25