Re: [Qemu-devel] Tracing: outstanding tasks

[Stefan Hajnoczi]

On Fri, Jul 2, 2010 at 5:23 AM, Ananth N Mavinakayanahalli
<address@hidden> wrote:
> On Wed, Jun 30, 2010 at 12:51:59PM +0100, Stefan Hajnoczi wrote:
>> On Wed, Jun 30, 2010 at 11:20 AM, Prerna Saxena
>> <address@hidden> wrote:
>> > On 06/26/2010 01:36 PM, Stefan Hajnoczi wrote:
>> >>
>> >> Here are the outstanding tasks for QEMU tracing, which Prerna and I have
>> >> been working on.  Tracing aids debugging, profiling, and observing
>> >> execution via lightweight logging at key points in the code path.
>
> ...
>
>> >> 5. Out-of-line trace file write-out
>> >>
>> >> Owner: Stefan
>> >>
>> >> Trace buffers are written out to file synchronously.  The vcpu thread
>> >> should
>> >> not be blocked so an async write-out mechanism is needed.
>> >>
>> >> 6. Trace file command
>> >>
>> >> Owner: ?
>> >>
>> >> Traces are written out to hardcoded /tmp/trace.log.  This must be
>> >> configurable.
>> >> Tracing at startup time should still be possible so configuration needs to
>> >> happen early.
>
> Another feature needed would be a facility to trigger a sync of trace buffer 
> to
> file even if the buffer isn't full.

Good idea.  A related piece that is not in the current tracing branch
is syncing to trace buffer to file on exit.  Right now a partially
filled trace buffer is not written when QEMU exits.

Stefan