Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Fri, 7 Feb 2020 11:56:40 +0100 | Subject | Re: [PATCH -v2 08/10] m68k,mm: Extend table allocator for multiple sizes |
| |
Hoi Peter,
On Fri, Jan 31, 2020 at 1:56 PM Peter Zijlstra <peterz@infradead.org> wrote: > In addition to the PGD/PMD table size (128*4) add a PTE table size > (64*4) to the table allocator. This completely removes the pte-table > overhead compared to the old code, even for dense tables.
Thanks for your patch!
> Notes: > > - the allocator gained a list_empty() check to deal with there not > being any pages at all. > > - the free mask is extended to cover more than the 8 bits required > for the (512 byte) PGD/PMD tables.
Being an mm-illiterate, I don't understand the relation between the number of bits and the size (see below).
> - NR_PAGETABLE accounting is restored. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
WARNING: Missing Signed-off-by: line by nominal patch author 'Peter Zijlstra <peterz@infradead.org>' (in all patches)
I can fix that (the From?) up while applying.
> --- a/arch/m68k/mm/motorola.c > +++ b/arch/m68k/mm/motorola.c > @@ -72,24 +72,35 @@ void mmu_page_dtor(void *page) > arch/sparc/mm/srmmu.c ... */ > > typedef struct list_head ptable_desc; > -static LIST_HEAD(ptable_list); > + > +static struct list_head ptable_list[2] = { > + LIST_HEAD_INIT(ptable_list[0]), > + LIST_HEAD_INIT(ptable_list[1]), > +}; > > #define PD_PTABLE(page) ((ptable_desc *)&(virt_to_page(page)->lru)) > #define PD_PAGE(ptable) (list_entry(ptable, struct page, lru)) > -#define PD_MARKBITS(dp) (*(unsigned char *)&PD_PAGE(dp)->index) > +#define PD_MARKBITS(dp) (*(unsigned int *)&PD_PAGE(dp)->index) > + > +static const int ptable_shift[2] = { > + 7+2, /* PGD, PMD */ > + 6+2, /* PTE */ > +}; > > -#define PTABLE_SIZE (PTRS_PER_PMD * sizeof(pmd_t)) > +#define ptable_size(type) (1U << ptable_shift[type]) > +#define ptable_mask(type) ((1U << (PAGE_SIZE / ptable_size(type))) - 1)
So this is 0xff for PGD and PMD, like before, and 0xffff for PTE. Why the latter value?
Thanks!
> > -void __init init_pointer_table(unsigned long ptable) > +void __init init_pointer_table(void *table, int type) > { > ptable_desc *dp; > + unsigned long ptable = (unsigned long)table; > unsigned long page = ptable & PAGE_MASK; > - unsigned char mask = 1 << ((ptable - page)/PTABLE_SIZE); > + unsigned int mask = 1U << ((ptable - page)/ptable_size(type)); > > dp = PD_PTABLE(page); > if (!(PD_MARKBITS(dp) & mask)) { > - PD_MARKBITS(dp) = 0xff; > - list_add(dp, &ptable_list); > + PD_MARKBITS(dp) = ptable_mask(type); > + list_add(dp, &ptable_list[type]); > } > > PD_MARKBITS(dp) &= ~mask;
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
| |