Commit 5709f7cf authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman

powerpc/mm/slice: implement a slice mask cache

Calculating the slice mask can become a signifcant overhead for
get_unmapped_area. This patch adds a struct slice_mask for
each page size in the mm_context, and keeps these in synch with
the slices psize arrays and slb_addr_limit.

On Book3S/64 this adds 288 bytes to the mm_context_t for the
slice mask caches.

On POWER8, this increases vfork+exec+exit performance by 9.9%
and reduces time to mmap+munmap a 64kB page by 28%.

Reduces time to mmap+munmap by about 10% on 8xx.
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 830fd2d4
......@@ -80,6 +80,16 @@ struct spinlock;
/* Maximum possible number of NPUs in a system. */
#define NV_MAX_NPUS 8
/*
* One bit per slice. We have lower slices which cover 256MB segments
* upto 4G range. That gets us 16 low slices. For the rest we track slices
* in 1TB size.
*/
struct slice_mask {
u64 low_slices;
DECLARE_BITMAP(high_slices, SLICE_NUM_HIGH);
};
typedef struct {
mm_context_id_t id;
u16 user_psize; /* page size index */
......@@ -95,6 +105,14 @@ typedef struct {
unsigned char low_slices_psize[BITS_PER_LONG / BITS_PER_BYTE];
unsigned char high_slices_psize[SLICE_ARRAY_SIZE];
unsigned long slb_addr_limit;
# ifdef CONFIG_PPC_64K_PAGES
struct slice_mask mask_64k;
# endif
struct slice_mask mask_4k;
# ifdef CONFIG_HUGETLB_PAGE
struct slice_mask mask_16m;
struct slice_mask mask_16g;
# endif
#else
u16 sllp; /* SLB page size encoding */
#endif
......
......@@ -192,6 +192,11 @@
#endif
#ifndef __ASSEMBLY__
struct slice_mask {
u64 low_slices;
DECLARE_BITMAP(high_slices, 0);
};
typedef struct {
unsigned int id;
unsigned int active;
......@@ -201,6 +206,11 @@ typedef struct {
unsigned char low_slices_psize[SLICE_ARRAY_SIZE];
unsigned char high_slices_psize[0];
unsigned long slb_addr_limit;
struct slice_mask mask_base_psize; /* 4k or 16k */
# ifdef CONFIG_HUGETLB_PAGE
struct slice_mask mask_512k;
struct slice_mask mask_8m;
# endif
#endif
} mm_context_t;
......
......@@ -37,15 +37,6 @@
#include <asm/hugetlb.h>
static DEFINE_SPINLOCK(slice_convert_lock);
/*
* One bit per slice. We have lower slices which cover 256MB segments
* upto 4G range. That gets us 16 low slices. For the rest we track slices
* in 1TB size.
*/
struct slice_mask {
u64 low_slices;
DECLARE_BITMAP(high_slices, SLICE_NUM_HIGH);
};
#ifdef DEBUG
int _slice_debug = 1;
......@@ -149,36 +140,39 @@ static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret,
__set_bit(i, ret->high_slices);
}
static void slice_mask_for_size(struct mm_struct *mm, int psize, struct slice_mask *ret,
unsigned long high_limit)
#ifdef CONFIG_PPC_BOOK3S_64
static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
{
unsigned char *hpsizes, *lpsizes;
int index, mask_index;
unsigned long i;
ret->low_slices = 0;
if (SLICE_NUM_HIGH)
bitmap_zero(ret->high_slices, SLICE_NUM_HIGH);
lpsizes = mm->context.low_slices_psize;
for (i = 0; i < SLICE_NUM_LOW; i++) {
mask_index = i & 0x1;
index = i >> 1;
if (((lpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
ret->low_slices |= 1u << i;
}
if (high_limit <= SLICE_LOW_TOP)
return;
hpsizes = mm->context.high_slices_psize;
for (i = 0; i < GET_HIGH_SLICE_INDEX(high_limit); i++) {
mask_index = i & 0x1;
index = i >> 1;
if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
__set_bit(i, ret->high_slices);
}
#ifdef CONFIG_PPC_64K_PAGES
if (psize == MMU_PAGE_64K)
return &mm->context.mask_64k;
#endif
if (psize == MMU_PAGE_4K)
return &mm->context.mask_4k;
#ifdef CONFIG_HUGETLB_PAGE
if (psize == MMU_PAGE_16M)
return &mm->context.mask_16m;
if (psize == MMU_PAGE_16G)
return &mm->context.mask_16g;
#endif
BUG();
}
#elif defined(CONFIG_PPC_8xx)
static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
{
if (psize == mmu_virtual_psize)
return &mm->context.mask_base_psize;
#ifdef CONFIG_HUGETLB_PAGE
if (psize == MMU_PAGE_512K)
return &mm->context.mask_512k;
if (psize == MMU_PAGE_8M)
return &mm->context.mask_8m;
#endif
BUG();
}
#else
#error "Must define the slice masks for page sizes supported by the platform"
#endif
static int slice_check_fit(struct mm_struct *mm,
const struct slice_mask *mask,
......@@ -225,11 +219,15 @@ static void slice_convert(struct mm_struct *mm,
int index, mask_index;
/* Write the new slice psize bits */
unsigned char *hpsizes, *lpsizes;
struct slice_mask *psize_mask, *old_mask;
unsigned long i, flags;
int old_psize;
slice_dbg("slice_convert(mm=%p, psize=%d)\n", mm, psize);
slice_print_mask(" mask", mask);
psize_mask = slice_mask_for_size(mm, psize);
/* We need to use a spinlock here to protect against
* concurrent 64k -> 4k demotion ...
*/
......@@ -242,6 +240,14 @@ static void slice_convert(struct mm_struct *mm,
mask_index = i & 0x1;
index = i >> 1;
/* Update the slice_mask */
old_psize = (lpsizes[index] >> (mask_index * 4)) & 0xf;
old_mask = slice_mask_for_size(mm, old_psize);
old_mask->low_slices &= ~(1u << i);
psize_mask->low_slices |= 1u << i;
/* Update the sizes array */
lpsizes[index] = (lpsizes[index] & ~(0xf << (mask_index * 4))) |
(((unsigned long)psize) << (mask_index * 4));
}
......@@ -253,6 +259,14 @@ static void slice_convert(struct mm_struct *mm,
mask_index = i & 0x1;
index = i >> 1;
/* Update the slice_mask */
old_psize = (hpsizes[index] >> (mask_index * 4)) & 0xf;
old_mask = slice_mask_for_size(mm, old_psize);
__clear_bit(i, old_mask->high_slices);
__set_bit(i, psize_mask->high_slices);
/* Update the sizes array */
hpsizes[index] = (hpsizes[index] & ~(0xf << (mask_index * 4))) |
(((unsigned long)psize) << (mask_index * 4));
}
......@@ -463,7 +477,13 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
}
if (high_limit > mm->context.slb_addr_limit) {
/*
* Increasing the slb_addr_limit does not require
* slice mask cache to be recalculated because it should
* be already initialised beyond the old address limit.
*/
mm->context.slb_addr_limit = high_limit;
on_each_cpu(slice_flush_segments, mm, 1);
}
......@@ -505,7 +525,7 @@ 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
*/
slice_mask_for_size(mm, psize, &good_mask, high_limit);
good_mask = *slice_mask_for_size(mm, psize);
slice_print_mask(" good_mask", &good_mask);
/*
......@@ -530,7 +550,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
#ifdef CONFIG_PPC_64K_PAGES
/* If we support combo pages, we can allow 64k pages in 4k slices */
if (psize == MMU_PAGE_64K) {
slice_mask_for_size(mm, MMU_PAGE_4K, &compat_mask, high_limit);
compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
if (fixed)
slice_or_mask(&good_mask, &compat_mask);
}
......@@ -682,6 +702,7 @@ EXPORT_SYMBOL_GPL(get_slice_psize);
void slice_init_new_context_exec(struct mm_struct *mm)
{
unsigned char *hpsizes, *lpsizes;
struct slice_mask *mask;
unsigned int psize = mmu_virtual_psize;
slice_dbg("slice_init_new_context_exec(mm=%p)\n", mm);
......@@ -707,6 +728,14 @@ void slice_init_new_context_exec(struct mm_struct *mm)
hpsizes = mm->context.high_slices_psize;
memset(hpsizes, (psize << 4) | psize, SLICE_NUM_HIGH >> 1);
/*
* Slice mask cache starts zeroed, fill the default size cache.
*/
mask = slice_mask_for_size(mm, psize);
mask->low_slices = ~0UL;
if (SLICE_NUM_HIGH)
bitmap_fill(mask->high_slices, SLICE_NUM_HIGH);
}
void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
......@@ -745,18 +774,17 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
{
struct slice_mask mask, available;
unsigned int psize = mm->context.user_psize;
unsigned long high_limit = mm->context.slb_addr_limit;
if (radix_enabled())
return 0;
slice_range_to_mask(addr, len, &mask);
slice_mask_for_size(mm, psize, &available, high_limit);
available = *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;
slice_mask_for_size(mm, MMU_PAGE_4K, &compat_mask, high_limit);
compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
slice_or_mask(&available, &compat_mask);
}
#endif
......
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