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Re: [libvirt] PATCH: 6/25: Avoid event loop wakups in remote driver



On Thu, Jan 15, 2009 at 03:19:39PM +0100, Jim Meyering wrote:
> "Daniel P. Berrange" <berrange redhat com> wrote:
> > When going into the call() method, we temporarily disable the
> > event wakup callback. The call() method is already processing
> > any async messages which arrive, so letting the main event loop
> > wakup here is inefficient, and indeed will block the main event
> > loop on the mutex while the main thread is in call(). We really
> > don't want that !
> >
> >  remote_internal.c |   42 ++++++++++++++++++++++++++++++++++--------
> >  1 file changed, 34 insertions(+), 8 deletions(-)
> >
> > Daniel
> >
> > diff --git a/src/remote_internal.c b/src/remote_internal.c
> ...
> > +doCall (virConnectPtr conn, struct private_data *priv,
> ...
> > +static int
> > +call (virConnectPtr conn, struct private_data *priv,
> > +      int flags /* if we are in virConnectOpen */,
> > +      int proc_nr,
> > +      xdrproc_t args_filter, char *args,
> > +      xdrproc_t ret_filter, char *ret)
> > +{
> > +    int rv;
> > +    /*
> > +     * Avoid needless wake-ups of the event loop in the
> > +     * case where this call is being made from a different
> > +     * thread than the event loop. These wake-ups would
> > +     * cause the event loop thread to be blocked on the
> > +     * mutex for the duration of the call
> > +     */
> > +    if (priv->watch >= 0)
> > +        virEventUpdateHandle(priv->watch, 0);
> > +
> > +    rv = doCall(conn, priv,flags, proc_nr,
> > +                args_filter, args,
> > +                ret_filter, ret);
> > +
> > +    if (priv->watch >= 0)
> > +        virEventUpdateHandle(priv->watch, VIR_EVENT_HANDLE_READABLE);
> 
> Looks fine.  ACK.

Comitted this

Daniel
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