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authorDennis Zhou <dennis@kernel.org>2019-02-25 14:10:15 -0800
committerDennis Zhou <dennis@kernel.org>2019-03-13 12:25:31 -0700
commitda3afdd5bb5428fd38b4b64f2d5e897c3bb78354 (patch)
tree561003eb63655cdbb8f8bae8912b46a8f0f5e93b /mm
parentb89462a9c5f4a3ac5160e7b3599bb09c94b94880 (diff)
percpu: use block scan_hint to only scan forward
Blocks now remember the latest scan_hint. This can be used on the allocation path as when a contig_hint is broken, we can promote the scan_hint to the contig_hint and scan forward from there. This works because pcpu_block_refresh_hint() is only called on the allocation path while block free regions are updated manually in pcpu_block_update_hint_free(). Signed-off-by: Dennis Zhou <dennis@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/percpu.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/mm/percpu.c b/mm/percpu.c
index b82f3cacf2ed..c5250e162d4d 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -761,14 +761,23 @@ static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
{
struct pcpu_block_md *block = chunk->md_blocks + index;
unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
- int rs, re; /* region start, region end */
+ int rs, re, start; /* region start, region end */
+
+ /* promote scan_hint to contig_hint */
+ if (block->scan_hint) {
+ start = block->scan_hint_start + block->scan_hint;
+ block->contig_hint_start = block->scan_hint_start;
+ block->contig_hint = block->scan_hint;
+ block->scan_hint = 0;
+ } else {
+ start = block->first_free;
+ block->contig_hint = 0;
+ }
- /* clear hints */
- block->contig_hint = block->scan_hint = 0;
- block->left_free = block->right_free = 0;
+ block->right_free = 0;
/* iterate over free areas and update the contig hints */
- pcpu_for_each_unpop_region(alloc_map, rs, re, block->first_free,
+ pcpu_for_each_unpop_region(alloc_map, rs, re, start,
PCPU_BITMAP_BLOCK_BITS) {
pcpu_block_update(block, rs, re);
}
@@ -833,6 +842,8 @@ static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
s_off,
s_off + bits)) {
/* block contig hint is broken - scan to fix it */
+ if (!s_off)
+ s_block->left_free = 0;
pcpu_block_refresh_hint(chunk, s_index);
} else {
/* update left and right contig manually */
@@ -866,11 +877,11 @@ static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
if (e_off > e_block->scan_hint_start)
e_block->scan_hint = 0;
+ e_block->left_free = 0;
if (e_off > e_block->contig_hint_start) {
/* contig hint is broken - scan to fix it */
pcpu_block_refresh_hint(chunk, e_index);
} else {
- e_block->left_free = 0;
e_block->right_free =
min_t(int, e_block->right_free,
PCPU_BITMAP_BLOCK_BITS - e_off);