[HarfBuzz] Amiri and OpenType performance

[Behdad Esfahbod]

BTW, disabling 'kern' makes it more than twice faster!

On 13-04-15 03:59 PM, Behdad Esfahbod wrote:
> On 13-04-15 03:52 PM, Khaled Hosny wrote:
>> On Mon, Apr 15, 2013 at 03:48:26PM -0400, Behdad Esfahbod wrote:
>>> On a private thread (which I wish was on the public list) with Konstantin we
>>> were measuring performance of harfbuzz-ng vs old and I noticed that shaping
>>> with Amiri roughly involves hundreds of lookups.  Unfortunately OpenType
>>> shaping runtime is at best linear in the number of lookups.  Any chance you
>>> can look into possibly consolidating some of those?
>>
>> I didn’t consider this before, but probably I can do something. How do
>> you measure the performance?
> 
> Added --num-iterations for that.
> 
> I'm testing with:
> 
> $ echo "هو أمّا حكومة القاذفات مكن, وفي تنفّس الشرقي لهيمنة أن. هو قام هزيمة
> وأزيز اندلاع, ومن أي وبداية الواقعة. و إخضاع" | time hb-shape
> ~/fonts/amiri-0.105/amiri-regular.ttf --output-file /dev/null --shaper old
> --num-iterations=10000
> 8.88user 0.00system 0:08.91elapsed 99%CPU (0avgtext+0avgdata 17120maxresident)k
> 0inputs+0outputs (0major+1190minor)pagefaults 0swaps
> 
> Note that if I choose the fallback shaper, essentially 98.5% of the time goes
> away! :(
> 
> $ echo "هو أمّا حكومة القاذفات مكن, وفي تنفّس الشرقي لهيمنة أن. هو قام هزيمة
> وأزيز اندلاع, ومن أي وبداية الواقعة. و إخضاع" | time hb-shape
> ~/fonts/amiri-0.105/amiri-regular.ttf --output-file /dev/null --shaper old
> --num-iterations=10000 --shaper fallback
> 0.15user 0.00system 0:00.15elapsed 99%CPU (0avgtext+0avgdata 12976maxresident)k
> 0inputs+0outputs (0major+899minor)pagefaults 0swaps
> 
> 
> I'll be looking for ideas to speed these up.  But given the popularity that
> Amiri is gaining on the web, would be nice to try to optimize on both sides.
> 
> behdad
> 
> 
> 
> 
>> Regards,
>> Khaled
>>
> 

-- 
behdad
http://behdad.org/