16 bit float precision

Q139

Hi,
I am thinking of using half precision float to reduce memory usage as my software has large vectors of floats.

Can I expect faster performance as less data requests from ram?
Am I correc to assume that decimal precision of float16 is about 3-4decimal places?
Is this fastest implementation of this data type or should look for other libraries?
https://doc.qt.io/qt-5/qfloat16.html

JonB

@Q139 said in 16 bit float precision:

Can I expect faster performance as less data requests from ram?

I note the docs say:

This implies that any arithmetic operation on a qfloat16 instance results in the value first being converted to a float. This conversion to and from float is performed by hardware when possible, but on processors that do not natively support half-precision, the conversion is performed through a sequence of lookup table operations.

I don't know, does your hardware support half-precision floats?

aha_1980

Hi @Q139,

just to add to @JonB's good answer:

Introduction to float 16 bit is here: https://en.wikipedia.org/wiki/Half-precision_floating-point_format

Can I expect faster performance as less data requests from ram?

The only correct answer to this question is: profile your program and decide afterwards.

Regards

SimonSchroeder

I guess that half precision has been supported on GPUs for a while now. I thought this to be a relatively new feature on CPUs. However, here is an article from 2012 by Intel explaining hardware support for loading/storing (including conversion) of half precision floats: https://software.intel.com/content/www/us/en/develop/articles/performance-benefits-of-half-precision-floats.html

So, I guess you can assume half precision floats on comparatively recent computers.

Q139

It worked out as good idea and,improved performance in my case(accessing 15+gb float arrays from ram)
Probably with each ram access it was pulling twice as much to cpu cache and less ram access wait for cpu.

Pablo J. Rogina

@Q139 said in 16 bit float precision:

It worked out as good idea

Nice, are you able to mark your post as solved then? Thanks.