Re: [PATCH olang v3] arena: optimization: ensure alignment memory access

[Johnny Richard <johnny@johnnyrichard.com>]

Fantastic patch, I don't think we need a new revision at all.  I have
just comments for the commit message. And if you agree on changing it, we
can apply then changes when during patch-apply.

Let me know what you think. Otherwise I can apply it.

Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>

On Wed, Feb 28, 2024 at 11:25:34AM -0300, Carlos Maniero wrote:
> This commit changes the pointers returned by *arena_alloc* to always be
> 16 bytes aligned. Non-aligned data structure could have a huge impact on

nitpick:
s/Non-aligned/Unaligned/

> performance. Take the example bellow:
> 
>   int main() {
>       void *pointer = malloc(1024);

Let's use an "uint8_t *" pointer to be safer here.  Pointer arithmetics
with "void *" pointers a unpredictable.

> 
>       int offset = 0;

*int* is not a good type to store a pointer offset since it cannot
address all possible offsets.  I know that for this test is fine...

**size_t** is a better type for this kind of operations.

>       long long* data = pointer + offset;

*long long* might have different size depending on the platform you are
running.  If you want the example to be more complete you should
describe on which platforming you are running this test.

> 
>       for (int i = 0; i < INT_MAX; i++) {
>           *data += i;
>       }
> 
>       printf("result = %lld", *data);
>   }
> 
> These are the execution times in my machine:

Perhaps describe **my machine** details? **x86_64** right?