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mm: remove free_area_cache use in powerpc architecture
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As all other architectures have been converted to use vm_unmapped_area(),
we are about to retire the free_area_cache.

This change simply removes the use of that cache in
slice_get_unmapped_area(), which will most certainly have a
performance cost. Next one will convert that function to use the
vm_unmapped_area() infrastructure and regain the performance.

Signed-off-by: Michel Lespinasse <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: "Aneesh Kumar K.V" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>
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@walken-google @ozbenh
walken-google authored and ozbenh committed Apr 30, 2013
1 parent 3925f46 commit 34d0717
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Showing 4 changed files with 22 additions and 93 deletions.
3 changes: 1 addition & 2 deletions arch/powerpc/include/asm/page_64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -99,8 +99,7 @@ extern unsigned long slice_get_unmapped_area(unsigned long addr,
unsigned long len,
unsigned long flags,
unsigned int psize,
int topdown,
int use_cache);
int topdown);

extern unsigned int get_slice_psize(struct mm_struct *mm,
unsigned long addr);
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2 changes: 1 addition & 1 deletion arch/powerpc/mm/hugetlbpage.c
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Original file line number Diff line number Diff line change
Expand Up @@ -742,7 +742,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
struct hstate *hstate = hstate_file(file);
int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));

return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1, 0);
return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
}
#endif

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108 changes: 19 additions & 89 deletions arch/powerpc/mm/slice.c
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Original file line number Diff line number Diff line change
Expand Up @@ -240,23 +240,15 @@ static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psiz
static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
unsigned long len,
struct slice_mask available,
int psize, int use_cache)
int psize)
{
struct vm_area_struct *vma;
unsigned long start_addr, addr;
unsigned long addr;
struct slice_mask mask;
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

if (use_cache) {
if (len <= mm->cached_hole_size) {
start_addr = addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
} else
start_addr = addr = mm->free_area_cache;
} else
start_addr = addr = TASK_UNMAPPED_BASE;
addr = TASK_UNMAPPED_BASE;

full_search:
for (;;) {
addr = _ALIGN_UP(addr, 1ul << pshift);
if ((TASK_SIZE - len) < addr)
Expand All @@ -272,63 +264,24 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
addr = _ALIGN_UP(addr + 1, 1ul << SLICE_HIGH_SHIFT);
continue;
}
if (!vma || addr + len <= vma->vm_start) {
/*
* Remember the place where we stopped the search:
*/
if (use_cache)
mm->free_area_cache = addr + len;
if (!vma || addr + len <= vma->vm_start)
return addr;
}
if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;
addr = vma->vm_end;
}

/* Make sure we didn't miss any holes */
if (use_cache && start_addr != TASK_UNMAPPED_BASE) {
start_addr = addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
goto full_search;
}
return -ENOMEM;
}

static unsigned long slice_find_area_topdown(struct mm_struct *mm,
unsigned long len,
struct slice_mask available,
int psize, int use_cache)
int psize)
{
struct vm_area_struct *vma;
unsigned long addr;
struct slice_mask mask;
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

/* check if free_area_cache is useful for us */
if (use_cache) {
if (len <= mm->cached_hole_size) {
mm->cached_hole_size = 0;
mm->free_area_cache = mm->mmap_base;
}

/* either no address requested or can't fit in requested
* address hole
*/
addr = mm->free_area_cache;

/* make sure it can fit in the remaining address space */
if (addr > len) {
addr = _ALIGN_DOWN(addr - len, 1ul << pshift);
mask = slice_range_to_mask(addr, len);
if (slice_check_fit(mask, available) &&
slice_area_is_free(mm, addr, len))
/* remember the address as a hint for
* next time
*/
return (mm->free_area_cache = addr);
}
}

addr = mm->mmap_base;
while (addr > len) {
/* Go down by chunk size */
Expand All @@ -352,16 +305,8 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
* return with success:
*/
vma = find_vma(mm, addr);
if (!vma || (addr + len) <= vma->vm_start) {
/* remember the address as a hint for next time */
if (use_cache)
mm->free_area_cache = addr;
if (!vma || (addr + len) <= vma->vm_start)
return addr;
}

/* remember the largest hole we saw so far */
if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;

/* try just below the current vma->vm_start */
addr = vma->vm_start;
Expand All @@ -373,28 +318,18 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
* can happen with large stack limits and large mmap()
* allocations.
*/
addr = slice_find_area_bottomup(mm, len, available, psize, 0);

/*
* Restore the topdown base:
*/
if (use_cache) {
mm->free_area_cache = mm->mmap_base;
mm->cached_hole_size = ~0UL;
}

return addr;
return slice_find_area_bottomup(mm, len, available, psize);
}


static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
struct slice_mask mask, int psize,
int topdown, int use_cache)
int topdown)
{
if (topdown)
return slice_find_area_topdown(mm, len, mask, psize, use_cache);
return slice_find_area_topdown(mm, len, mask, psize);
else
return slice_find_area_bottomup(mm, len, mask, psize, use_cache);
return slice_find_area_bottomup(mm, len, mask, psize);
}

#define or_mask(dst, src) do { \
Expand All @@ -415,7 +350,7 @@ static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,

unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
unsigned long flags, unsigned int psize,
int topdown, int use_cache)
int topdown)
{
struct slice_mask mask = {0, 0};
struct slice_mask good_mask;
Expand All @@ -430,8 +365,8 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
BUG_ON(mm->task_size == 0);

slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize);
slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d, use_cache=%d\n",
addr, len, flags, topdown, use_cache);
slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n",
addr, len, flags, topdown);

if (len > mm->task_size)
return -ENOMEM;
Expand Down Expand Up @@ -503,8 +438,7 @@ 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, psize, topdown,
use_cache);
newaddr = slice_find_area(mm, len, good_mask, psize, topdown);
if (newaddr != -ENOMEM) {
/* Found within the good mask, we don't have to setup,
* we thus return directly
Expand Down Expand Up @@ -536,8 +470,7 @@ 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, psize, topdown,
use_cache);
addr = slice_find_area(mm, len, good_mask, psize, topdown);
if (addr != -ENOMEM) {
slice_dbg(" found area at 0x%lx\n", addr);
return addr;
Expand All @@ -547,15 +480,14 @@ 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, psize, topdown,
use_cache);
addr = slice_find_area(mm, len, potential_mask, psize, topdown);

#ifdef CONFIG_PPC_64K_PAGES
if (addr == -ENOMEM && psize == MMU_PAGE_64K) {
/* retry the search with 4k-page slices included */
or_mask(potential_mask, compat_mask);
addr = slice_find_area(mm, len, potential_mask, psize,
topdown, use_cache);
topdown);
}
#endif

Expand Down Expand Up @@ -586,8 +518,7 @@ unsigned long arch_get_unmapped_area(struct file *filp,
unsigned long flags)
{
return slice_get_unmapped_area(addr, len, flags,
current->mm->context.user_psize,
0, 1);
current->mm->context.user_psize, 0);
}

unsigned long arch_get_unmapped_area_topdown(struct file *filp,
Expand All @@ -597,8 +528,7 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
const unsigned long flags)
{
return slice_get_unmapped_area(addr0, len, flags,
current->mm->context.user_psize,
1, 1);
current->mm->context.user_psize, 1);
}

unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr)
Expand Down
2 changes: 1 addition & 1 deletion arch/powerpc/platforms/cell/spufs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -352,7 +352,7 @@ static unsigned long spufs_get_unmapped_area(struct file *file,

/* Else, try to obtain a 64K pages slice */
return slice_get_unmapped_area(addr, len, flags,
MMU_PAGE_64K, 1, 0);
MMU_PAGE_64K, 1);
}
#endif /* CONFIG_SPU_FS_64K_LS */

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