[Qemu-devel] Re: [PATCH] simpletrace: Thread-safe tracing

[Paolo Bonzini]

On 02/27/2011 06:02 PM, Stefan Hajnoczi wrote:
> On Sun, Feb 27, 2011 at 3:13 PM, Paolo Bonzini<address@hidden>  wrote:
> > On 02/27/2011 03:58 PM, Stefan Hajnoczi wrote:
> > > + * Trace records are written out by a dedicated thread.  The thread waits
> > > for
> > > + * records to become available, writes them out, and then waits again.
> > > + */
> > > +static pthread_mutex_t trace_lock = PTHREAD_MUTEX_INITIALIZER;
> > > +static pthread_cond_t trace_available_cond = PTHREAD_COND_INITIALIZER;
> > > +static pthread_cond_t trace_empty_cond = PTHREAD_COND_INITIALIZER;
> > > +static bool trace_available;
> > > +static bool trace_writeout_enabled;
> >
> > Please use QemuThread.
>
> The tracing code itself should use avoid core QEMU code.  Otherwise we
> can't trace QemuThread - we'd have an infinite loop.

Hmm, right... they'll use stdio to trace Win32 then... :)  I was 
actually thinking more of the code duplication.

But do you really need tracing at such a low level?  I'd expect tracing 
wrappers like qemu_lock_mutex_iothread, not mutexes in general.

Paolo