On 2023-04-07 09:01:29, Sean Christopherson wrote:
> On Fri, Apr 07, 2023, Bagas Sanjaya wrote:
> > On Fri, Apr 07, 2023 at 05:31:47AM -0400, Kautuk Consul wrote:
> > > I used the unlikely() macro on the return values of the k.alloc
> > > calls and found that it changes the code generation a bit.
> > > Optimize all return paths of k.alloc calls by improving
> > > branch prediction on return value of k.alloc.
>
> Nit, this is improving code generation, not branch prediction.
Sorry my mistake.
>
> > What about below?
> >
> > "Improve branch prediction on kmalloc() and kzalloc() call by using
> > unlikely() macro to optimize their return paths."
>
> Another nit, using unlikely() doesn't necessarily provide a measurable
> optimization.
> As above, it does often improve code generation for the happy path, but that
> doesn't
> always equate to improved performance, e.g. if the CPU can easily predict the
> branch
> and/or there is no impact on the cache footprint.
I see. I will submit a v2 of the patch with a better and more accurate
description. Does anyone else have any comments before I do so ?
