powerpc/mm/slice: pass pointers to struct slice_mask where possible

Pass around const pointers to struct slice_mask where possible, rather
than copies of slice_mask, to reduce stack and call overhead.

checkstack.pl gives, before:
0x00000d1c slice_get_unmapped_area [slice.o]:		592
0x00001864 is_hugepage_only_range [slice.o]:		448
0x00000754 slice_find_area_topdown [slice.o]:		400
0x00000484 slice_find_area_bottomup.isra.1 [slice.o]:	272
0x000017b4 slice_set_range_psize [slice.o]:		224
0x00000a4c slice_find_area [slice.o]:			128
0x00000160 slice_check_fit [slice.o]:			112

after:
0x00000ad0 slice_get_unmapped_area [slice.o]:		448
0x00001464 is_hugepage_only_range [slice.o]:		288
0x000006c0 slice_find_area [slice.o]:			144
0x0000016c slice_check_fit [slice.o]:			128
0x00000528 slice_find_area_bottomup.isra.2 [slice.o]:	128
0x000013e4 slice_set_range_psize [slice.o]:		128

This increases vfork+exec+exit performance by 1.5%.

Reduces time to mmap+munmap a 64kB page by 17%.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 432c328b3e9418828a8e85c1d5fe11f0c03cbcc5..420d791f0e182e27458ba15ac64265b24a15bd74 100644 (file)
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -50,19 +50,21 @@ struct slice_mask {
 #ifdef DEBUG
 int _slice_debug = 1;
 
-static void slice_print_mask(const char *label, struct slice_mask mask)
+static void slice_print_mask(const char *label, const struct slice_mask *mask)
 {
        if (!_slice_debug)
                return;
-       pr_devel("%s low_slice: %*pbl\n", label, (int)SLICE_NUM_LOW, &mask.low_slices);
-       pr_devel("%s high_slice: %*pbl\n", label, (int)SLICE_NUM_HIGH, mask.high_slices);
+       pr_devel("%s low_slice: %*pbl\n", label,
+                       (int)SLICE_NUM_LOW, &mask->low_slices);
+       pr_devel("%s high_slice: %*pbl\n", label,
+                       (int)SLICE_NUM_HIGH, mask->high_slices);
 }
 
 #define slice_dbg(fmt...) do { if (_slice_debug) pr_devel(fmt); } while (0)
 
 #else
 
-static void slice_print_mask(const char *label, struct slice_mask mask) {}
+static void slice_print_mask(const char *label, const struct slice_mask *mask) {}
 #define slice_dbg(fmt...)
 
 #endif
@@ -179,7 +181,8 @@ static void slice_mask_for_size(struct mm_struct *mm, int psize, struct slice_ma
 }
 
 static int slice_check_fit(struct mm_struct *mm,
-                          struct slice_mask mask, struct slice_mask available)
+                          const struct slice_mask *mask,
+                          const struct slice_mask *available)
 {
        DECLARE_BITMAP(result, SLICE_NUM_HIGH);
        /*
@@ -189,14 +192,14 @@ static int slice_check_fit(struct mm_struct *mm,
        unsigned long slice_count = GET_HIGH_SLICE_INDEX(mm->context.slb_addr_limit);
 
        if (!SLICE_NUM_HIGH)
-               return (mask.low_slices & available.low_slices) ==
-                      mask.low_slices;
+               return (mask->low_slices & available->low_slices) ==
+                      mask->low_slices;
 
-       bitmap_and(result, mask.high_slices,
-                  available.high_slices, slice_count);
+       bitmap_and(result, mask->high_slices,
+                  available->high_slices, slice_count);
 
-       return (mask.low_slices & available.low_slices) == mask.low_slices &&
-               bitmap_equal(result, mask.high_slices, slice_count);
+       return (mask->low_slices & available->low_slices) == mask->low_slices &&
+               bitmap_equal(result, mask->high_slices, slice_count);
 }
 
 static void slice_flush_segments(void *parm)
@@ -216,7 +219,8 @@ static void slice_flush_segments(void *parm)
 #endif
 }
 
-static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psize)
+static void slice_convert(struct mm_struct *mm,
+                               const struct slice_mask *mask, int psize)
 {
        int index, mask_index;
        /* Write the new slice psize bits */
@@ -233,7 +237,7 @@ static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psiz
 
        lpsizes = mm->context.low_slices_psize;
        for (i = 0; i < SLICE_NUM_LOW; i++) {
-               if (!(mask.low_slices & (1u << i)))
+               if (!(mask->low_slices & (1u << i)))
                        continue;
 
                mask_index = i & 0x1;
@@ -244,7 +248,7 @@ static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psiz
 
        hpsizes = mm->context.high_slices_psize;
        for (i = 0; i < GET_HIGH_SLICE_INDEX(mm->context.slb_addr_limit); i++) {
-               if (!test_bit(i, mask.high_slices))
+               if (!test_bit(i, mask->high_slices))
                        continue;
 
                mask_index = i & 0x1;
@@ -270,26 +274,25 @@ static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psiz
  * 'available' slice_mark.
  */
 static bool slice_scan_available(unsigned long addr,
-                                struct slice_mask available,
-                                int end,
-                                unsigned long *boundary_addr)
+                                const struct slice_mask *available,
+                                int end, unsigned long *boundary_addr)
 {
        unsigned long slice;
        if (addr < SLICE_LOW_TOP) {
                slice = GET_LOW_SLICE_INDEX(addr);
                *boundary_addr = (slice + end) << SLICE_LOW_SHIFT;
-               return !!(available.low_slices & (1u << slice));
+               return !!(available->low_slices & (1u << slice));
        } else {
                slice = GET_HIGH_SLICE_INDEX(addr);
                *boundary_addr = (slice + end) ?
                        ((slice + end) << SLICE_HIGH_SHIFT) : SLICE_LOW_TOP;
-               return !!test_bit(slice, available.high_slices);
+               return !!test_bit(slice, available->high_slices);
        }
 }
 
 static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
                                              unsigned long len,
-                                             struct slice_mask available,
+                                             const struct slice_mask *available,
                                              int psize, unsigned long high_limit)
 {
        int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
@@ -335,7 +338,7 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 
 static unsigned long slice_find_area_topdown(struct mm_struct *mm,
                                             unsigned long len,
-                                            struct slice_mask available,
+                                            const struct slice_mask *available,
                                             int psize, unsigned long high_limit)
 {
        int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
@@ -393,7 +396,7 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 
 
 static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
-                                    struct slice_mask mask, int psize,
+                                    const struct slice_mask *mask, int psize,
                                     int topdown, unsigned long high_limit)
 {
        if (topdown)
@@ -402,7 +405,8 @@ static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
                return slice_find_area_bottomup(mm, len, mask, psize, high_limit);
 }
 
-static inline void slice_or_mask(struct slice_mask *dst, struct slice_mask *src)
+static inline void slice_or_mask(struct slice_mask *dst,
+                                       const struct slice_mask *src)
 {
        dst->low_slices |= src->low_slices;
        if (!SLICE_NUM_HIGH)
@@ -411,7 +415,8 @@ static inline void slice_or_mask(struct slice_mask *dst, struct slice_mask *src)
                  SLICE_NUM_HIGH);
 }
 
-static inline void slice_andnot_mask(struct slice_mask *dst, struct slice_mask *src)
+static inline void slice_andnot_mask(struct slice_mask *dst,
+                                       const struct slice_mask *src)
 {
        dst->low_slices &= ~src->low_slices;
 
@@ -501,7 +506,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
         * already
         */
        slice_mask_for_size(mm, psize, &good_mask, high_limit);
-       slice_print_mask(" good_mask", good_mask);
+       slice_print_mask(" good_mask", &good_mask);
 
        /*
         * Here "good" means slices that are already the right page size,
@@ -535,12 +540,12 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
        if (addr != 0 || fixed) {
                /* Build a mask for the requested range */
                slice_range_to_mask(addr, len, &mask);
-               slice_print_mask(" mask", mask);
+               slice_print_mask(" mask", &mask);
 
                /* Check if we fit in the good mask. If we do, we just return,
                 * nothing else to do
                 */
-               if (slice_check_fit(mm, mask, good_mask)) {
+               if (slice_check_fit(mm, &mask, &good_mask)) {
                        slice_dbg(" fits good !\n");
                        return addr;
                }
@@ -548,7 +553,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
                /* Now let's see if we can find something in the existing
                 * slices for that size
                 */
-               newaddr = slice_find_area(mm, len, good_mask,
+               newaddr = slice_find_area(mm, len, &good_mask,
                                          psize, topdown, high_limit);
                if (newaddr != -ENOMEM) {
                        /* Found within the good mask, we don't have to setup,
@@ -564,9 +569,10 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
         */
        slice_mask_for_free(mm, &potential_mask, high_limit);
        slice_or_mask(&potential_mask, &good_mask);
-       slice_print_mask(" potential", potential_mask);
+       slice_print_mask(" potential", &potential_mask);
 
-       if ((addr != 0 || fixed) && slice_check_fit(mm, mask, potential_mask)) {
+       if ((addr != 0 || fixed) &&
+                       slice_check_fit(mm, &mask, &potential_mask)) {
                slice_dbg(" fits potential !\n");
                goto convert;
        }
@@ -581,7 +587,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
         * anywhere in the good area.
         */
        if (addr) {
-               addr = slice_find_area(mm, len, good_mask,
+               addr = slice_find_area(mm, len, &good_mask,
                                       psize, topdown, high_limit);
                if (addr != -ENOMEM) {
                        slice_dbg(" found area at 0x%lx\n", addr);
@@ -592,14 +598,14 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
        /* Now let's see if we can find something in the existing slices
         * for that size plus free slices
         */
-       addr = slice_find_area(mm, len, potential_mask,
+       addr = slice_find_area(mm, len, &potential_mask,
                               psize, topdown, high_limit);
 
 #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, &compat_mask);
-               addr = slice_find_area(mm, len, potential_mask,
+               addr = slice_find_area(mm, len, &potential_mask,
                                       psize, topdown, high_limit);
        }
 #endif
@@ -609,7 +615,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
 
        slice_range_to_mask(addr, len, &mask);
        slice_dbg(" found potential area at 0x%lx\n", addr);
-       slice_print_mask(" mask", mask);
+       slice_print_mask(" mask", &mask);
 
  convert:
        slice_andnot_mask(&mask, &good_mask);
@@ -617,7 +623,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
        if (mask.low_slices ||
            (SLICE_NUM_HIGH &&
             !bitmap_empty(mask.high_slices, SLICE_NUM_HIGH))) {
-               slice_convert(mm, mask, psize);
+               slice_convert(mm, &mask, psize);
                if (psize > MMU_PAGE_BASE)
                        on_each_cpu(slice_flush_segments, mm, 1);
        }
@@ -711,7 +717,7 @@ void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
        VM_BUG_ON(radix_enabled());
 
        slice_range_to_mask(start, len, &mask);
-       slice_convert(mm, mask, psize);
+       slice_convert(mm, &mask, psize);
 }
 
 #ifdef CONFIG_HUGETLB_PAGE
@@ -758,9 +764,9 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
 #if 0 /* too verbose */
        slice_dbg("is_hugepage_only_range(mm=%p, addr=%lx, len=%lx)\n",
                 mm, addr, len);
-       slice_print_mask(" mask", mask);
-       slice_print_mask(" available", available);
+       slice_print_mask(" mask", &mask);
+       slice_print_mask(" available", &available);
 #endif
-       return !slice_check_fit(mm, mask, available);
+       return !slice_check_fit(mm, &mask, &available);
 }
 #endif