ES3.1 Proposal Working Draft

Mike Cowlishaw MFC at uk.ibm.com
Tue Feb 26 00:04:19 PST 2008


> If you don't think imposing a 2x slowdown on web apps is a showstopper 
> then clearly we have very different views on performance. (Note, using 
> your high estimate of two orders of magnitude it would be a 6x 
> slowdown if 5% of an application's time [not instructions] is spent in 
> floating point arithmetic.)

And if it were 1% in FP arithmetic and one order of magnitude, it would be 
a 1.1x (10%) slowdown.
 
>  From my point of view, this would be a massive regression and 
> conclusively rules out the idea of replacing binary floating point 
> with decimal floating point in ECMAScript.

I too would like to see high performance and the correct results in 
calculations.  And I would rather see correct results with slower 
performance than fast results with incorrect results.  As a result of the 
latter, many apps are forced to go back to the server for 'business 
logic', which has a disastrous effect on response times to the user (but 
at least, on the server, apps now have the option of decimal FP hardware).

But as you are more concerned with client-side performance, I think, can 
you show us a real script that spends anything like 5% of its time in 
floating-point arithmetic?  I failed to create an artificial one that used 
as much as that (but that was a few years ago; today's ECMAScript engines 
might have different characteristics).

Mike





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