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: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
Michael Ellerman
Родитель
830fd2d45a
Коммит
5709f7cfd8
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@ -80,6 +80,16 @@ struct spinlock;
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/* Maximum possible number of NPUs in a system. */
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#define NV_MAX_NPUS 8
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/*
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* One bit per slice. We have lower slices which cover 256MB segments
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* upto 4G range. That gets us 16 low slices. For the rest we track slices
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* in 1TB size.
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*/
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struct slice_mask {
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u64 low_slices;
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DECLARE_BITMAP(high_slices, SLICE_NUM_HIGH);
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};
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typedef struct {
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mm_context_id_t id;
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u16 user_psize; /* page size index */
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@ -95,6 +105,14 @@ typedef struct {
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unsigned char low_slices_psize[BITS_PER_LONG / BITS_PER_BYTE];
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unsigned char high_slices_psize[SLICE_ARRAY_SIZE];
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unsigned long slb_addr_limit;
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# ifdef CONFIG_PPC_64K_PAGES
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struct slice_mask mask_64k;
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# endif
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struct slice_mask mask_4k;
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# ifdef CONFIG_HUGETLB_PAGE
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struct slice_mask mask_16m;
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struct slice_mask mask_16g;
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# endif
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#else
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u16 sllp; /* SLB page size encoding */
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#endif
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@ -192,6 +192,11 @@
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#endif
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#ifndef __ASSEMBLY__
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struct slice_mask {
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u64 low_slices;
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DECLARE_BITMAP(high_slices, 0);
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};
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typedef struct {
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unsigned int id;
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unsigned int active;
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@ -201,6 +206,11 @@ typedef struct {
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unsigned char low_slices_psize[SLICE_ARRAY_SIZE];
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unsigned char high_slices_psize[0];
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unsigned long slb_addr_limit;
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struct slice_mask mask_base_psize; /* 4k or 16k */
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# ifdef CONFIG_HUGETLB_PAGE
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struct slice_mask mask_512k;
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struct slice_mask mask_8m;
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# endif
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#endif
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} mm_context_t;
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@ -37,15 +37,6 @@
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#include <asm/hugetlb.h>
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static DEFINE_SPINLOCK(slice_convert_lock);
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/*
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* One bit per slice. We have lower slices which cover 256MB segments
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* upto 4G range. That gets us 16 low slices. For the rest we track slices
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* in 1TB size.
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*/
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struct slice_mask {
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u64 low_slices;
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DECLARE_BITMAP(high_slices, SLICE_NUM_HIGH);
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};
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#ifdef DEBUG
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int _slice_debug = 1;
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@ -149,36 +140,39 @@ static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret,
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__set_bit(i, ret->high_slices);
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}
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static void slice_mask_for_size(struct mm_struct *mm, int psize, struct slice_mask *ret,
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unsigned long high_limit)
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#ifdef CONFIG_PPC_BOOK3S_64
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static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
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{
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unsigned char *hpsizes, *lpsizes;
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int index, mask_index;
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unsigned long i;
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ret->low_slices = 0;
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if (SLICE_NUM_HIGH)
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bitmap_zero(ret->high_slices, SLICE_NUM_HIGH);
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lpsizes = mm->context.low_slices_psize;
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for (i = 0; i < SLICE_NUM_LOW; i++) {
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mask_index = i & 0x1;
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index = i >> 1;
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if (((lpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
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ret->low_slices |= 1u << i;
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}
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if (high_limit <= SLICE_LOW_TOP)
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return;
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hpsizes = mm->context.high_slices_psize;
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for (i = 0; i < GET_HIGH_SLICE_INDEX(high_limit); i++) {
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mask_index = i & 0x1;
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index = i >> 1;
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if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
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__set_bit(i, ret->high_slices);
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}
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#ifdef CONFIG_PPC_64K_PAGES
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if (psize == MMU_PAGE_64K)
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return &mm->context.mask_64k;
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#endif
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if (psize == MMU_PAGE_4K)
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return &mm->context.mask_4k;
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#ifdef CONFIG_HUGETLB_PAGE
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if (psize == MMU_PAGE_16M)
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return &mm->context.mask_16m;
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if (psize == MMU_PAGE_16G)
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return &mm->context.mask_16g;
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#endif
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BUG();
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}
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#elif defined(CONFIG_PPC_8xx)
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static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
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{
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if (psize == mmu_virtual_psize)
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return &mm->context.mask_base_psize;
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#ifdef CONFIG_HUGETLB_PAGE
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if (psize == MMU_PAGE_512K)
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return &mm->context.mask_512k;
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if (psize == MMU_PAGE_8M)
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return &mm->context.mask_8m;
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#endif
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BUG();
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}
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#else
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#error "Must define the slice masks for page sizes supported by the platform"
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#endif
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static int slice_check_fit(struct mm_struct *mm,
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const struct slice_mask *mask,
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@ -225,11 +219,15 @@ static void slice_convert(struct mm_struct *mm,
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int index, mask_index;
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/* Write the new slice psize bits */
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unsigned char *hpsizes, *lpsizes;
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struct slice_mask *psize_mask, *old_mask;
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unsigned long i, flags;
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int old_psize;
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slice_dbg("slice_convert(mm=%p, psize=%d)\n", mm, psize);
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slice_print_mask(" mask", mask);
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psize_mask = slice_mask_for_size(mm, psize);
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/* We need to use a spinlock here to protect against
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* concurrent 64k -> 4k demotion ...
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*/
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@ -242,6 +240,14 @@ static void slice_convert(struct mm_struct *mm,
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mask_index = i & 0x1;
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index = i >> 1;
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/* Update the slice_mask */
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old_psize = (lpsizes[index] >> (mask_index * 4)) & 0xf;
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old_mask = slice_mask_for_size(mm, old_psize);
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old_mask->low_slices &= ~(1u << i);
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psize_mask->low_slices |= 1u << i;
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/* Update the sizes array */
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lpsizes[index] = (lpsizes[index] & ~(0xf << (mask_index * 4))) |
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(((unsigned long)psize) << (mask_index * 4));
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}
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@ -253,6 +259,14 @@ static void slice_convert(struct mm_struct *mm,
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mask_index = i & 0x1;
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index = i >> 1;
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/* Update the slice_mask */
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old_psize = (hpsizes[index] >> (mask_index * 4)) & 0xf;
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old_mask = slice_mask_for_size(mm, old_psize);
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__clear_bit(i, old_mask->high_slices);
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__set_bit(i, psize_mask->high_slices);
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/* Update the sizes array */
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hpsizes[index] = (hpsizes[index] & ~(0xf << (mask_index * 4))) |
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(((unsigned long)psize) << (mask_index * 4));
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}
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@ -463,7 +477,13 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
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}
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if (high_limit > mm->context.slb_addr_limit) {
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/*
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* Increasing the slb_addr_limit does not require
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* slice mask cache to be recalculated because it should
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* be already initialised beyond the old address limit.
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*/
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mm->context.slb_addr_limit = high_limit;
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on_each_cpu(slice_flush_segments, mm, 1);
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}
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@ -505,7 +525,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
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/* First make up a "good" mask of slices that have the right size
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* already
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*/
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slice_mask_for_size(mm, psize, &good_mask, high_limit);
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good_mask = *slice_mask_for_size(mm, psize);
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slice_print_mask(" good_mask", &good_mask);
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/*
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@ -530,7 +550,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
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#ifdef CONFIG_PPC_64K_PAGES
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/* If we support combo pages, we can allow 64k pages in 4k slices */
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if (psize == MMU_PAGE_64K) {
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slice_mask_for_size(mm, MMU_PAGE_4K, &compat_mask, high_limit);
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compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
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if (fixed)
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slice_or_mask(&good_mask, &compat_mask);
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}
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@ -682,6 +702,7 @@ EXPORT_SYMBOL_GPL(get_slice_psize);
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void slice_init_new_context_exec(struct mm_struct *mm)
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{
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unsigned char *hpsizes, *lpsizes;
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struct slice_mask *mask;
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unsigned int psize = mmu_virtual_psize;
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slice_dbg("slice_init_new_context_exec(mm=%p)\n", mm);
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@ -707,6 +728,14 @@ void slice_init_new_context_exec(struct mm_struct *mm)
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hpsizes = mm->context.high_slices_psize;
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memset(hpsizes, (psize << 4) | psize, SLICE_NUM_HIGH >> 1);
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/*
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* Slice mask cache starts zeroed, fill the default size cache.
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*/
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mask = slice_mask_for_size(mm, psize);
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mask->low_slices = ~0UL;
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if (SLICE_NUM_HIGH)
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bitmap_fill(mask->high_slices, SLICE_NUM_HIGH);
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}
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void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
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@ -745,18 +774,17 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
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{
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struct slice_mask mask, available;
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unsigned int psize = mm->context.user_psize;
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unsigned long high_limit = mm->context.slb_addr_limit;
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if (radix_enabled())
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return 0;
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slice_range_to_mask(addr, len, &mask);
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slice_mask_for_size(mm, psize, &available, high_limit);
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available = *slice_mask_for_size(mm, psize);
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#ifdef CONFIG_PPC_64K_PAGES
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/* We need to account for 4k slices too */
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if (psize == MMU_PAGE_64K) {
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struct slice_mask compat_mask;
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slice_mask_for_size(mm, MMU_PAGE_4K, &compat_mask, high_limit);
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compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
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slice_or_mask(&available, &compat_mask);
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}
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#endif
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