[PATCH v5 2/7] malloc: Add THP/madvise support for sbrk

[DJ Delorie]

LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>

Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org> writes:
> diff --git a/include/libc-pointer-arith.h b/include/libc-pointer-arith.h
>  #define PTR_ALIGN_UP(base, size) \
>    ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size)))
>  
> +/* Check if BASE is aligned on SIZE  */
> +#define PTR_IS_ALIGNED(base, size) \
> +  ((((uintptr_t) (base)) & (size - 1)) == 0)
> +
> +/* Returns the ptrdiff_t diference between P1 and P2.  */
> +#define PTR_DIFF(p1, p2) \
> +  ((ptrdiff_t)((uintptr_t)(p1) - (uintptr_t)(p2)))
> +

Ok.

> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index b8103aaf10..8a66012503 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -2023,6 +2023,16 @@ madvise_thp (void *p, INTERNAL_SIZE_T size)
>       not active.  */
>    if (mp_.thp_pagesize == 0 || size < mp_.thp_pagesize)
>      return;
> +
> +  /* Linux requires the input address to be page-aligned, and unaligned
> +     inputs happens only for initial data segment.  */
> +  if (__glibc_unlikely (!PTR_IS_ALIGNED (p, GLRO (dl_pagesize))))
> +    {
> +      void *q = PTR_ALIGN_DOWN (p, GLRO (dl_pagesize));
> +      size += PTR_DIFF (p, q);
> +      p = q;
> +    }
> +
>    __madvise (p, size, MADV_HUGEPAGE);

Ok.

> @@ -2609,14 +2619,25 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
> -         Round to a multiple of page size.
> +         Round to a multiple of page size or huge page size.

Ok.

> -      size = ALIGN_UP (size, pagesize);
> +#if HAVE_TUNABLES && defined (MADV_HUGEPAGE)
> +      /* Defined in brk.c.  */
> +      extern void *__curbrk;
> +      if (__glibc_unlikely (mp_.thp_pagesize != 0))
> +	{
> +	  uintptr_t top = ALIGN_UP ((uintptr_t) __curbrk + size,
> +				    mp_.thp_pagesize);
> +	  size = top - (uintptr_t) __curbrk;
> +	}
> +      else
> +#endif
> +	size = ALIGN_UP (size, GLRO(dl_pagesize));

Ok.

>        /*
>           Don't try to call MORECORE if argument is so big as to appear
> @@ -2899,10 +2920,8 @@ systrim (size_t pad, mstate av)
>    long released;         /* Amount actually released */
>    char *current_brk;     /* address returned by pre-check sbrk call */
>    char *new_brk;         /* address returned by post-check sbrk call */
> -  size_t pagesize;
>    long top_area;
>  
> -  pagesize = GLRO (dl_pagesize);
>    top_size = chunksize (av->top);
>  
>    top_area = top_size - MINSIZE - 1;
> @@ -2910,7 +2929,12 @@ systrim (size_t pad, mstate av)
>      return 0;
>  
>    /* Release in pagesize units and round down to the nearest page.  */
> -  extra = ALIGN_DOWN(top_area - pad, pagesize);
> +#if HAVE_TUNABLES && defined (MADV_HUGEPAGE)
> +  if (__glibc_unlikely (mp_.thp_pagesize != 0))
> +    extra = ALIGN_DOWN (top_area - pad, mp_.thp_pagesize);
> +  else
> +#endif
> +    extra = ALIGN_DOWN (top_area - pad, GLRO(dl_pagesize));
>  
>    if (extra == 0)
>      return 0;

Ok.