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Groups > linux.kernel > #1695253
| From | Dennis Zhou <dennisz@fb.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 17/23] percpu: skip chunks if the alloc does not fit in the contig hint |
| Date | 2017-07-25 01:10 +0200 |
| Message-ID | <u6UEb-3ig-53@gated-at.bofh.it> (permalink) |
| References | <u6UE9-3ig-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>
This patch adds chunk->contig_bits_start to keep track of the contig
hint's offset and the check to skip the chunk if it does not fit. If
the chunk's contig hint starting offset cannot satisfy an allocation,
the allocator assumes there is enough memory pressure in this chunk to
either use a different chunk or create a new one. This accepts a less
tight packing for a smoother latency curve.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
---
mm/percpu-internal.h | 2 ++
mm/percpu.c | 18 ++++++++++++++++--
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index e60e049..7065faf 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -29,6 +29,8 @@ struct pcpu_chunk {
struct list_head list; /* linked to pcpu_slot lists */
int free_bytes; /* free bytes in the chunk */
int contig_bits; /* max contiguous size hint */
+ int contig_bits_start; /* contig_bits starting
+ offset */
void *base_addr; /* base address of this chunk */
unsigned long *alloc_map; /* allocation map */
diff --git a/mm/percpu.c b/mm/percpu.c
index ad70c67..3732373 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -393,12 +393,14 @@ static inline int pcpu_cnt_pop_pages(struct pcpu_chunk *chunk, int bit_off,
* @bit_off: chunk offset
* @bits: size of free area
*
- * This updates the chunk's contig hint given a free area.
+ * This updates the chunk's contig hint and starting offset given a free area.
*/
static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits)
{
- if (bits > chunk->contig_bits)
+ if (bits > chunk->contig_bits) {
+ chunk->contig_bits_start = bit_off;
chunk->contig_bits = bits;
+ }
}
/**
@@ -409,6 +411,7 @@ static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits)
*
* Updates:
* chunk->contig_bits
+ * chunk->contig_bits_start
* nr_empty_pop_pages
*/
static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk)
@@ -639,6 +642,17 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
int bit_off, bits;
int re; /* region end */
+ /*
+ * Check to see if the allocation can fit in the chunk's contig hint.
+ * This is an optimization to prevent scanning by assuming if it
+ * cannot fit in the global hint, there is memory pressure and creating
+ * a new chunk would happen soon.
+ */
+ bit_off = ALIGN(chunk->contig_bits_start, align) -
+ chunk->contig_bits_start;
+ if (bit_off + alloc_bits > chunk->contig_bits)
+ return -1;
+
pcpu_for_each_unpop_region(chunk->alloc_map, bit_off, re,
chunk->first_bit,
pcpu_chunk_map_bits(chunk)) {
--
2.9.3
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[PATCH v2 00/23] percpu: replace percpu area map allocator with bitmap allocator Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
[PATCH v2 22/23] percpu: update pcpu_find_block_fit to use an iterator Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 22/23] percpu: update pcpu_find_block_fit to use an iterator Josef Bacik <josef@toxicpanda.com> - 2017-07-25 21:50 +0200
[PATCH v2 09/23] percpu: combine percpu address checks Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 09/23] percpu: combine percpu address checks Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:30 +0200
[PATCH v2 02/23] percpu: introduce start_offset to pcpu_chunk Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 02/23] percpu: introduce start_offset to pcpu_chunk Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:10 +0200
[PATCH v2 13/23] percpu: generalize bitmap (un)populated iterators Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 13/23] percpu: generalize bitmap (un)populated iterators Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:40 +0200
Re: [PATCH v2 13/23] percpu: generalize bitmap (un)populated iterators Tejun Heo <tj@kernel.org> - 2017-07-26 16:10 +0200
[PATCH v2 08/23] percpu: modify base_addr to be region specific Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 08/23] percpu: modify base_addr to be region specific Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:30 +0200
[PATCH v2 17/23] percpu: skip chunks if the alloc does not fit in the contig hint Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 17/23] percpu: skip chunks if the alloc does not fit in the contig hint Josef Bacik <josef@toxicpanda.com> - 2017-07-25 21:50 +0200
[PATCH v2 19/23] percpu: update alloc path to only scan if contig hints are broken Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 19/23] percpu: update alloc path to only scan if contig hints are broken Josef Bacik <josef@toxicpanda.com> - 2017-07-25 21:40 +0200
[PATCH v2 12/23] percpu: increase minimum percpu allocation size and align first regions Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:10 +0200
Re: [PATCH v2 12/23] percpu: increase minimum percpu allocation size and align first regions Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:40 +0200
[PATCH v2 01/23] percpu: setup_first_chunk enforce dynamic region must exist Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:20 +0200
Re: [PATCH v2 01/23] percpu: setup_first_chunk enforce dynamic region must exist Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:10 +0200
[PATCH v2 06/23] percpu: end chunk area maps page aligned for the populated bitmap Dennis Zhou <dennisz@fb.com> - 2017-07-25 01:20 +0200
Re: [PATCH v2 06/23] percpu: end chunk area maps page aligned for the populated bitmap Josef Bacik <josef@toxicpanda.com> - 2017-07-25 20:20 +0200
Re: [PATCH v2 14/23] percpu: replace area map allocator with bitmap allocator Josef Bacik <josef@toxicpanda.com> - 2017-07-25 21:20 +0200
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