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authorDennis Zhou (Facebook) <dennisszhou@gmail.com>2017-07-24 19:02:08 -0400
committerTejun Heo <tj@kernel.org>2017-07-26 10:23:53 -0400
commit0cecf50cf00fbe6858908098ae6c6a9fd1d60724 (patch)
treeb44770aa79749b55e338dc0309d618e7baf0435a /mm/percpu.c
parent8ab16c43ea79098f4126432c6b199a5d6ba24b6d (diff)
download96b-common-0cecf50cf00fbe6858908098ae6c6a9fd1d60724.tar.gz
percpu: introduce nr_empty_pop_pages to help empty page accounting
pcpu_nr_empty_pop_pages is used to ensure there are a handful of free pages around to serve atomic allocations. A new field, nr_empty_pop_pages, is added to the pcpu_chunk struct to keep track of the number of empty pages. This field is needed as the number of empty populated pages is globally tracked and deltas are used to update in the bitmap allocator. Pages that contain a hidden area are not considered to be empty. This new field is exposed in percpu_stats. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'mm/percpu.c')
-rw-r--r--mm/percpu.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/mm/percpu.c b/mm/percpu.c
index 773dafea181e..657ab0821cf0 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -757,11 +757,14 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
chunk->immutable = true;
bitmap_fill(chunk->populated, chunk->nr_pages);
chunk->nr_populated = chunk->nr_pages;
+ chunk->nr_empty_pop_pages = chunk->nr_pages;
chunk->contig_hint = chunk->free_size = map_size;
if (chunk->start_offset) {
/* hide the beginning of the bitmap */
+ chunk->nr_empty_pop_pages--;
+
chunk->map[0] = 1;
chunk->map[1] = chunk->start_offset;
chunk->map_used = 1;
@@ -773,6 +776,8 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
if (chunk->end_offset) {
/* hide the end of the bitmap */
+ chunk->nr_empty_pop_pages--;
+
chunk->map[++chunk->map_used] = region_size | 1;
}
@@ -836,6 +841,7 @@ static void pcpu_chunk_populated(struct pcpu_chunk *chunk,
bitmap_set(chunk->populated, page_start, nr);
chunk->nr_populated += nr;
+ chunk->nr_empty_pop_pages += nr;
pcpu_nr_empty_pop_pages += nr;
}
@@ -858,6 +864,7 @@ static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
bitmap_clear(chunk->populated, page_start, nr);
chunk->nr_populated -= nr;
+ chunk->nr_empty_pop_pages -= nr;
pcpu_nr_empty_pop_pages -= nr;
}
@@ -1782,9 +1789,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
/* link the first chunk in */
pcpu_first_chunk = chunk;
- i = (pcpu_first_chunk->start_offset) ? 1 : 0;
- pcpu_nr_empty_pop_pages +=
- pcpu_count_occupied_pages(pcpu_first_chunk, i);
+ pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
pcpu_chunk_relocate(pcpu_first_chunk, -1);
pcpu_stats_chunk_alloc();