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powerpc/mm/slice: Use const pointers to cached slice masks where possible

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The slice_mask cache was a basic conversion which copied the slice
mask into caller's structures, because that's how the original code
worked. In most cases the pointer can be used directly instead, saving
a copy and an on-stack structure.

On POWER8, this increases vfork+exec+exit performance by 0.3%
and reduces time to mmap+munmap a 64kB page by 2%.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-03-07 11:37:16 +10:00 committed by Michael Ellerman
parent 7490755830
commit d262bd5a73
1 changed files with 38 additions and 41 deletions
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79
arch/powerpc/mm/slice.c
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@ -468,10 +468,10 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
unsigned long flags, unsigned int psize,
int topdown)
{
struct slice_mask mask;
struct slice_mask good_mask;
struct slice_mask potential_mask;
struct slice_mask compat_mask;
const struct slice_mask *maskp;
const struct slice_mask *compat_maskp = NULL;
int fixed = (flags & MAP_FIXED);
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
unsigned long page_size = 1UL << pshift;
@ -505,22 +505,6 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
on_each_cpu(slice_flush_segments, mm, 1);
}
/*
* init different masks
*/
mask.low_slices = 0;
/* silence stupid warning */;
potential_mask.low_slices = 0;
compat_mask.low_slices = 0;
if (SLICE_NUM_HIGH) {
bitmap_zero(mask.high_slices, SLICE_NUM_HIGH);
bitmap_zero(potential_mask.high_slices, SLICE_NUM_HIGH);
bitmap_zero(compat_mask.high_slices, SLICE_NUM_HIGH);
}
/* Sanity checks */
BUG_ON(mm->task_size == 0);
BUG_ON(mm->context.slb_addr_limit == 0);
@ -543,8 +527,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
/* First make up a "good" mask of slices that have the right size
* already
*/
good_mask = *slice_mask_for_size(mm, psize);
slice_print_mask(" good_mask", &good_mask);
maskp = slice_mask_for_size(mm, psize);
/*
* Here "good" means slices that are already the right page size,
@ -565,14 +548,24 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
* search in good | compat | free, found => convert free.
*/
#ifdef CONFIG_PPC_64K_PAGES
/* If we support combo pages, we can allow 64k pages in 4k slices */
if (psize == MMU_PAGE_64K) {
compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
/*
* If we support combo pages, we can allow 64k pages in 4k slices
* The mask copies could be avoided in most cases here if we had
* a pointer to good mask for the next code to use.
*/
if (IS_ENABLED(CONFIG_PPC_64K_PAGES) && psize == MMU_PAGE_64K) {
compat_maskp = slice_mask_for_size(mm, MMU_PAGE_4K);
if (fixed)
slice_or_mask(&good_mask, &good_mask, &compat_mask);
slice_or_mask(&good_mask, maskp, compat_maskp);
else
slice_copy_mask(&good_mask, maskp);
} else {
slice_copy_mask(&good_mask, maskp);
}
#endif
slice_print_mask(" good_mask", &good_mask);
if (compat_maskp)
slice_print_mask(" compat_mask", compat_maskp);
/* First check hint if it's valid or if we have MAP_FIXED */
if (addr != 0 || fixed) {
@ -639,7 +632,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
#ifdef CONFIG_PPC_64K_PAGES
if (addr == -ENOMEM && psize == MMU_PAGE_64K) {
/* retry the search with 4k-page slices included */
slice_or_mask(&potential_mask, &potential_mask, &compat_mask);
slice_or_mask(&potential_mask, &potential_mask, compat_maskp);
addr = slice_find_area(mm, len, &potential_mask,
psize, topdown, high_limit);
}
@ -648,17 +641,18 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
if (addr == -ENOMEM)
return -ENOMEM;
slice_range_to_mask(addr, len, &mask);
slice_range_to_mask(addr, len, &potential_mask);
slice_dbg(" found potential area at 0x%lx\n", addr);
slice_print_mask(" mask", &mask);
slice_print_mask(" mask", &potential_mask);
convert:
slice_andnot_mask(&mask, &mask, &good_mask);
slice_andnot_mask(&mask, &mask, &compat_mask);
if (mask.low_slices ||
(SLICE_NUM_HIGH &&
!bitmap_empty(mask.high_slices, SLICE_NUM_HIGH))) {
slice_convert(mm, &mask, psize);
slice_andnot_mask(&potential_mask, &potential_mask, &good_mask);
if (compat_maskp && !fixed)
slice_andnot_mask(&potential_mask, &potential_mask, compat_maskp);
if (potential_mask.low_slices ||
(SLICE_NUM_HIGH &&
!bitmap_empty(potential_mask.high_slices, SLICE_NUM_HIGH))) {
slice_convert(mm, &potential_mask, psize);
if (psize > MMU_PAGE_BASE)
on_each_cpu(slice_flush_segments, mm, 1);
}
@ -787,22 +781,25 @@ void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
unsigned long len)
{
struct slice_mask available;
const struct slice_mask *maskp;
unsigned int psize = mm->context.user_psize;
if (radix_enabled())
return 0;
available = *slice_mask_for_size(mm, psize);
maskp = slice_mask_for_size(mm, psize);
#ifdef CONFIG_PPC_64K_PAGES
/* We need to account for 4k slices too */
if (psize == MMU_PAGE_64K) {
struct slice_mask compat_mask;
compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
slice_or_mask(&available, &available, &compat_mask);
const struct slice_mask *compat_maskp;
struct slice_mask available;
compat_maskp = slice_mask_for_size(mm, MMU_PAGE_4K);
slice_or_mask(&available, maskp, compat_maskp);
return !slice_check_range_fits(mm, &available, addr, len);
}
#endif
return !slice_check_range_fits(mm, &available, addr, len);
return !slice_check_range_fits(mm, maskp, addr, len);
}
#endif