Re: [PATCHv2] Add per-process flag to control thp

[Oleg Nesterov]

On 08/02, Alex Thorlton wrote:
>
> This patch implements functionality to allow processes to disable the use of
> transparent hugepages through the prctl syscall.
>
> We've determined that some jobs perform significantly better with thp disabled,
> and we needed a way to control thp on a per-process basis, without relying on
> madvise.

Well, I think the changelog should explain why madvise() is bad.

> @@ -1311,6 +1311,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
>  	p->sequential_io_avg	= 0;
>  #endif
>
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +	p->thp_disabled = current->thp_disabled;
> +#endif

Unneeded. It will be copied by dup_task_struct() automagically.

But I simply can't understand why this flag is per-thread. It should be
mm flag, no?

Oleg

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