Re: CVS commit: src/sys/uvm

[Taylor R Campbell <campbell+netbsd-source-changes-d%mumble.net@localhost>]

> Module Name:    src
> Committed By:   ad
> Date:           Sat Dec 21 14:41:44 UTC 2019
> 
> - Add inlines to set/get locator values in the unused lower bits of
>   pg->phys_addr.  Begin by using it to cache the freelist index, because
>   computing it is expensive and that shows up during profiling.  Discussed
>   on tech-kern.

So I guess we won't be switching pg->phys_addr from paddr to pfn?
Speaking of which, any plans for expanding to >32-bit (or >31-bit, if
signed) pfns in the rest of uvm?

> +static inline unsigned
> +uvm_page_get_bucket(struct vm_page *pg)
> +{
> +       return (pg->phys_addr & 0x3e0) >> 5;
> +}

Can you use __BITS/__SHIFTIN/__SHIFTOUT for this instead of magic hex
masks?

#define	PHYSADDR_FREELIST	__BITS(0,4)
#define PHYSADDR_BUCKET		__BITS(5,9)

static inline unsigned
uvm_page_get_bucket(struct vm_page *pg)
{
	return __SHIFTOUT(pg->phys_addr, PHYSADDR_BUCKET);
}

static inline unsigned
uvm_page_set_bucket(struct vm_page *pg, unsigned b)
{
	pg->phys_addr &= ~PHYSADDR_BUCKET;
	pg->phys_addr |= __SHIFTIN(b, PHYSADDR_BUCKET);
}