Bug 79739 – Use IPP malloc for AudioArray

• Component: Web Audio
• Status: RESOLVED WONTFIX

[Xingnan Wang]

IPP library provides the ippmalloc which can malloc memory aligned with 32-byte.
As AudioArray needs 16-byte alignment we can use ippmalloc instead.

[Xingnan Wang]

Created attachment 129177 [details]
Patch

[Xingnan Wang]

(In reply to comment #1)
> Created an attachment (id=129177) [details]
> Patch

Uploaded the patch, thanks.

[Chris Rogers]

Will 32-byte alignment get us any advantage over the 16-byte alignment?

[Xingnan Wang]

(In reply to comment #3)
> Will 32-byte alignment get us any advantage over the 16-byte alignment?

I think 32-byte and 16-byte alignment are not too much different here, I have to use it because the IPP only provides 32-byte aligned ippmalloc function. The advantage we can get is the aligned memory is more easily allocated than original way.

[Chris Rogers]

(In reply to comment #4)
> (In reply to comment #3)
> > Will 32-byte alignment get us any advantage over the 16-byte alignment?
> 
> I think 32-byte and 16-byte alignment are not too much different here, I have to use it because the IPP only provides 32-byte aligned ippmalloc function. The advantage we can get is the aligned memory is more easily allocated than original way.

I'm not sure what you mean by "more easily allocated".  I understand that the run-time code path in the IPP case would be slightly simpler in AudioArray.h, but is it actually a measurable performance win?
The disadvantage of having this special-casing is that the code is somewhat harder to read with this patch.  And this particular file is already somewhat tweaky even as it is right now, so it would be great to avoid adding additional complexity (harder to read through the code) unless there's a pretty good win.

[Julien Chaffraix]

Comment on attachment 129177 [details]
Patch

I agree with Chris here. If the switch leads to performance benefits then we should consider this change but in the absence of hard evidence or more substancial explanations, this is a maintenance burden on the project with little benefits.