[cairo] Regarding Cairo Optimization for ARM PXA320

Behdad Esfahbod behdad at behdad.org
Mon Oct 29 19:15:52 PDT 2007

On Mon, 2007-10-29 at 01:01 -0400, Sandeep Agrawal wrote:
> Hi,


> Actually I am unable to generate profiling data because of certain problems
> with the platform I am working on. I don't have permissions to create a new
> device and so opcontrol --init fails.

Then your first task should be to go get that permission.  As others
already pointed out, optimization without profiling makes little, if
any, sense.

> I am new to the text rendering field. Since Monahans does not have an FPU, I
> made the assumption that the affine transformations happening in floating
> point may be optimized to work in fixed point. Am I wrong in my assumption?

Yes.  We've optimized most of the easy fruit.  Only profiling your
specific use case shows what you should be working on.


> If so can you please give some hints as to where I can perform
> optimizations? I am sure that it would be possible to do some processor
> specific optimizations as well as Cairo has been written to cater to a large
> community.
> Thanks.
> Sandeep Agrawal,
> Wireless Terminal Division,
> Samsung India Software Operations.
> -----Original Message-----
> From: Dan Amelang [mailto:daniel.amelang at gmail.com] 
> Sent: Saturday, October 27, 2007 12:46 AM
> To: Sandeep Agrawal
> Cc: cairo at cairographics.org
> Subject: Re: [cairo] Regarding Cairo Optimization for ARM PXA320
> On 10/26/07, Sandeep Agrawal <sandeep.a at samsung.com> wrote:
> >
> > I am currently optimizing text rendering in Cairo for the PXA320 Monahans
> > processor.
> >
> > I just want to know that is it possible to convert the double computations
> > (specifically affine) to 16.16 or 26.6 fixed point format (any chance of
> > overflow or precision loss?)
> Yes, there is a chance of overflow and precision loss.
> > or do I have to go with processor specific
> > assembly optimizations?
> I don't see how this is an either/or situation. How did converting
> doubles to fixed-point and using assembly optimizations become your
> two options for text rendering improvement?
> I assume that your profiles show that floating-point emulation is the
> bottleneck? Can you share with us your data?
> Dan
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