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percpu: add first_bit to keep track of the first free in the bitmap

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This patch adds first_bit to keep track of the first free bit in the
bitmap. This hint helps prevent scanning of fully allocated blocks.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Dennis Zhou (Facebook) 2017-07-24 19:02:13 -04:00 committed by Tejun Heo
parent ca460b3c96
commit 86b442fbce
3 changed files with 17 additions and 3 deletions
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2
mm/percpu-internal.h
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@ -36,7 +36,7 @@ struct pcpu_chunk {
struct pcpu_block_md *md_blocks; /* metadata blocks */
void *data; /* chunk data */
int first_free; /* no free below this */
int first_bit; /* no free below this */
bool immutable; /* no [de]population allowed */
int start_offset; /* the overlap with the previous
region to have a page aligned

1
mm/percpu-stats.c
View file

@ -121,6 +121,7 @@ static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
P("nr_alloc", chunk->nr_alloc);
P("max_alloc_size", chunk->max_alloc_size);
P("empty_pop_pages", chunk->nr_empty_pop_pages);
P("first_bit", chunk->first_bit);
P("free_bytes", chunk->free_bytes);
P("contig_bytes", chunk->contig_bits * PCPU_MIN_ALLOC_SIZE);
P("sum_frag", sum_frag);

17
mm/percpu.c
View file

@ -427,7 +427,7 @@ static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk)
chunk->contig_bits = 0;
bits = nr_empty_pop_pages = 0;
pcpu_for_each_unpop_region(chunk->alloc_map, rs, re, 0,
pcpu_for_each_unpop_region(chunk->alloc_map, rs, re, chunk->first_bit,
pcpu_chunk_map_bits(chunk)) {
bits = re - rs;
@ -646,7 +646,8 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
int bit_off, bits;
int re; /* region end */
pcpu_for_each_unpop_region(chunk->alloc_map, bit_off, re, 0,
pcpu_for_each_unpop_region(chunk->alloc_map, bit_off, re,
chunk->first_bit,
pcpu_chunk_map_bits(chunk)) {
bits = re - bit_off;
@ -715,6 +716,13 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
/* update first free bit */
if (bit_off == chunk->first_bit)
chunk->first_bit = find_next_zero_bit(
chunk->alloc_map,
pcpu_chunk_map_bits(chunk),
bit_off + alloc_bits);
pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
pcpu_chunk_relocate(chunk, oslot);
@ -750,6 +758,9 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
/* update metadata */
chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE;
/* update first free bit */
chunk->first_bit = min(chunk->first_bit, bit_off);
pcpu_block_update_hint_free(chunk, bit_off, bits);
pcpu_chunk_relocate(chunk, oslot);
@ -841,6 +852,8 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
set_bit(0, chunk->bound_map);
set_bit(offset_bits, chunk->bound_map);
chunk->first_bit = offset_bits;
pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
}