Re: gdmgreeter CPU usage

["Padraig O'Briain" <Padraig Obriain Sun COM>]

I have dug deeper and found that indeed FcFontSort seems to be the
culprit. This function is called twice for each call to
pango_layout_line_get_extents and each call costs about 17 ms.

This accounts for most of the time.

I have also looked at greeter_session_init which is costing me 150 ms.
17 ms is due FcFontSort and 120 ms is due to FcInit.

Padraig

On Tue, 2006-01-10 at 09:02 +0000, Padraig O'Briain wrote:
> I am using DTrace scripts which I attach and the output which I also
> attach.
> 
> You will notice, see lines 29, 59, 103, 167, 231, that the calls to
> pango_layout_line_get_extents which are expensive, costing about 40 ms
> each, are the ones which open a font file.
> 
> I have not yet drilled down to see where the time is being spent or what
> the strings are.
> 
> What struck me was that we open Vera.ttf twice and VeraBd.ttf 3 times.
> If we opened each once it looks like we should save 120 ms.
> 
> I noticed in the news for pango 1.11.1 that you referred to caching
> optimizations. I was wondering these would cause these files to opened
> only once.
> 
> Padraig
> 
> On Mon, 2006-01-09 at 12:42 -0600, Federico Mena Quintero wrote:
> > On Mon, 2006-01-09 at 16:51 +0000, Padraig O'Briain wrote:
> > 
> > > I am using pango 1.10.1 and am looking at the CPU being used by
> > > gdmgreeter.
> > > 
> > > I have found that 25% of the CPU (about 200ms on my system) is used in 5
> > > calls to pango_layout_line_get_extents (called from
> > > gnome_canvas_text_set_property). Each call is associated with opening a
> > > TrueType font, two for Vera.ttf and three for VeraBd.ttf.
> > > 
> > > Do the improvements you have made in pango 1.11.1 offer me hope that
> > > this will be speeded up?
> > 
> > Do you have stack traces of where those calls happen?  Do you know which
> > strings are inside the corresponding PangoLayouts?
> > 
> > Do you have something like a sysprof log?
> > 
> > I wonder if the time is being spent directly inside Pango, or in
> > fontconfig/Xft loading fonts.
> > 
> > See bug #319483; we spend quite a bit of time in FcFontSort() when using
> > a font description that hasn't been used before.
> > 
> >   Federico
> > 
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