std.allocator needs your help

[Peter Alexander]

On Tuesday, 24 September 2013 at 15:25:11 UTC, Andrei 
Alexandrescu wrote:
>> What are they paying exactly? An extra arg to allocate that 
>> can probably
>> be defaulted?
>>   void[] allocate(size_t bytes, size_t align = this.alignment) 
>> shared;
>
> For allocating relatively small objects (say up to 32K), we're 
> looking at tens of cycles, no more. An extra argument needs to 
> be passed around and more importantly looked at and acted upon. 
> At this level it's a serious dent in the time budget.

The cost of a few cycles really doesn't matter for memory 
allocation... If you are really allocating memory so frequently 
that those few extra cycles matter then you are probably going to 
be memory bound anyway.

I think this is a situation where you need to justify yourself 
with something concrete. Can you provide an example of some code 
whose performance is significantly impacted by the addition of an 
alignment parameter? It has to be "real code" that does something 
useful, not just a loop the continually calls allocate.