From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH 06/10] powerpc/mm/slice: implement slice_check_range_fits
Date: Tue, 6 Mar 2018 23:25:03 +1000 [thread overview]
Message-ID: <20180306132507.10649-7-npiggin@gmail.com> (raw)
In-Reply-To: <20180306132507.10649-1-npiggin@gmail.com>
Rather than build slice masks from a range then use that to check for
fit in a candidate mask, implement slice_check_range_fits that checks
if a range fits in a mask directly.
This allows several structures to be removed from stacks, and also we
don't expect a huge range in a lot of these cases, so building and
comparing a full mask is going to be more expensive than testing just
one or two bits of the range.
On POWER8, this increases vfork+exec+exit performance by 0.3%
and reduces time to mmap+munmap a 64kB page by 5%.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/mm/slice.c | 63 ++++++++++++++++++++++++++-----------------------
1 file changed, 34 insertions(+), 29 deletions(-)
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 2115efe5e869..3841fca75006 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -179,26 +179,35 @@ static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
#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,
- const struct slice_mask *available)
+static bool slice_check_range_fits(struct mm_struct *mm,
+ const struct slice_mask *available,
+ unsigned long start, unsigned long len)
{
- DECLARE_BITMAP(result, SLICE_NUM_HIGH);
- /*
- * Make sure we just do bit compare only to the max
- * addr limit and not the full bit map size.
- */
- unsigned long slice_count = GET_HIGH_SLICE_INDEX(mm->context.slb_addr_limit);
+ unsigned long end = start + len - 1;
+ u64 low_slices = 0;
- if (!SLICE_NUM_HIGH)
- return (mask->low_slices & available->low_slices) ==
- mask->low_slices;
+ if (start < SLICE_LOW_TOP) {
+ unsigned long mend = min(end, (SLICE_LOW_TOP - 1));
+
+ low_slices = (1u << (GET_LOW_SLICE_INDEX(mend) + 1))
+ - (1u << GET_LOW_SLICE_INDEX(start));
+ }
+ if ((low_slices & available->low_slices) != low_slices)
+ return false;
+
+ if (SLICE_NUM_HIGH && ((start + len) > SLICE_LOW_TOP)) {
+ unsigned long start_index = GET_HIGH_SLICE_INDEX(start);
+ unsigned long align_end = ALIGN(end, (1UL << SLICE_HIGH_SHIFT));
+ unsigned long count = GET_HIGH_SLICE_INDEX(align_end) - start_index;
+ unsigned long i;
- bitmap_and(result, mask->high_slices,
- available->high_slices, slice_count);
+ for (i = start_index; i < start_index + count; i++) {
+ if (!test_bit(i, available->high_slices))
+ return false;
+ }
+ }
- return (mask->low_slices & available->low_slices) == mask->low_slices &&
- bitmap_equal(result, mask->high_slices, slice_count);
+ return true;
}
static void slice_flush_segments(void *parm)
@@ -562,15 +571,11 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
#endif
/* First check hint if it's valid or if we have MAP_FIXED */
- if (addr != 0 || fixed) {
- /* Build a mask for the requested range */
- slice_range_to_mask(addr, len, &mask);
- slice_print_mask(" mask", &mask);
-
+ if (addr || fixed) {
/* 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_range_fits(mm, &good_mask, addr, len)) {
slice_dbg(" fits good !\n");
return addr;
}
@@ -596,10 +601,11 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
slice_or_mask(&potential_mask, &good_mask);
slice_print_mask(" potential", &potential_mask);
- if ((addr != 0 || fixed) &&
- slice_check_fit(mm, &mask, &potential_mask)) {
- slice_dbg(" fits potential !\n");
- goto convert;
+ if (addr || fixed) {
+ if (slice_check_range_fits(mm, &potential_mask, addr, len)) {
+ slice_dbg(" fits potential !\n");
+ goto convert;
+ }
}
/* If we have MAP_FIXED and failed the above steps, then error out */
@@ -772,13 +778,12 @@ 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 mask, available;
+ struct slice_mask available;
unsigned int psize = mm->context.user_psize;
if (radix_enabled())
return 0;
- slice_range_to_mask(addr, len, &mask);
available = *slice_mask_for_size(mm, psize);
#ifdef CONFIG_PPC_64K_PAGES
/* We need to account for 4k slices too */
@@ -795,6 +800,6 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
slice_print_mask(" mask", &mask);
slice_print_mask(" available", &available);
#endif
- return !slice_check_fit(mm, &mask, &available);
+ return !slice_check_range_fits(mm, &available, addr, len);
}
#endif
--
2.16.1
next prev parent reply other threads:[~2018-03-06 13:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-06 13:24 [PATCH 00/10] powerpc/mm/slice: improve slice speed and stack use Nicholas Piggin
2018-03-06 13:24 ` [PATCH 01/10] selftests/powerpc: add process creation benchmark Nicholas Piggin
2018-03-19 22:23 ` [01/10] " Michael Ellerman
2018-03-20 10:15 ` Michael Ellerman
2018-03-06 13:24 ` [PATCH 02/10] powerpc/mm/slice: Simplify and optimise slice context initialisation Nicholas Piggin
2018-03-06 14:32 ` Nicholas Piggin
2018-03-06 13:25 ` [PATCH 03/10] powerpc/mm/slice: tidy lpsizes and hpsizes update loops Nicholas Piggin
2018-03-06 13:25 ` [PATCH 04/10] powerpc/mm/slice: pass pointers to struct slice_mask where possible Nicholas Piggin
2018-03-06 13:43 ` Christophe LEROY
2018-03-06 13:59 ` Nicholas Piggin
2018-03-06 13:25 ` [PATCH 05/10] powerpc/mm/slice: implement a slice mask cache Nicholas Piggin
2018-03-06 13:49 ` Christophe LEROY
2018-03-06 14:01 ` Nicholas Piggin
2018-03-06 13:25 ` Nicholas Piggin [this message]
2018-03-06 14:41 ` [PATCH 06/10] powerpc/mm/slice: implement slice_check_range_fits Christophe LEROY
2018-03-06 23:12 ` Nicholas Piggin
2018-03-07 6:12 ` Christophe LEROY
2018-03-07 7:16 ` Nicholas Piggin
2018-03-07 13:38 ` Christophe LEROY
2018-03-06 13:25 ` [PATCH 07/10] powerpc/mm/slice: Switch to 3-operand slice bitops helpers Nicholas Piggin
2018-03-06 14:44 ` Christophe LEROY
2018-03-06 23:19 ` Nicholas Piggin
2018-03-06 13:25 ` [PATCH 08/10] powerpc/mm/slice: Use const pointers to cached slice masks where possible Nicholas Piggin
2018-03-06 14:55 ` Christophe LEROY
2018-03-06 23:33 ` Nicholas Piggin
2018-03-06 13:25 ` [PATCH 09/10] powerpc/mm/slice: use the dynamic high slice size to limit bitmap operations Nicholas Piggin
2018-03-06 15:02 ` Christophe LEROY
2018-03-06 23:32 ` Nicholas Piggin
2018-03-06 13:25 ` [PATCH 10/10] powerpc/mm/slice: remove radix calls to the slice code Nicholas Piggin
2018-03-06 15:12 ` Christophe LEROY
2018-03-06 23:35 ` Nicholas Piggin
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