percpu: expose statistics about percpu memory via debugfs
There is limited visibility into the use of percpu memory leaving us
unable to reason about correctness of parameters and overall use of
percpu memory. These counters and statistics aim to help understand
basic statistics about percpu memory such as number of allocations over
the lifetime, allocation sizes, and fragmentation.
New Config: PERCPU_STATS
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/mm/percpu.c b/mm/percpu.c
index 75ac982..44a1cad 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -657,6 +657,7 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme,
int *p;
lockdep_assert_held(&pcpu_lock);
+ pcpu_stats_area_dealloc(chunk);
freeme |= 1; /* we are searching for <given offset, in use> pair */
@@ -721,6 +722,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
chunk->map[0] = 0;
chunk->map[1] = pcpu_unit_size | 1;
chunk->map_used = 1;
+ chunk->has_reserved = false;
INIT_LIST_HEAD(&chunk->list);
INIT_LIST_HEAD(&chunk->map_extend_list);
@@ -970,6 +972,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
goto restart;
area_found:
+ pcpu_stats_area_alloc(chunk, size);
spin_unlock_irqrestore(&pcpu_lock, flags);
/* populate if not all pages are already there */
@@ -1642,6 +1645,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
+ pcpu_stats_save_ai(ai);
+
/*
* Allocate chunk slots. The additional last slot is for
* empty chunks.
@@ -1685,6 +1690,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
if (schunk->free_size)
schunk->map[++schunk->map_used] = ai->static_size + schunk->free_size;
schunk->map[schunk->map_used] |= 1;
+ schunk->has_reserved = true;
/* init dynamic chunk if necessary */
if (dyn_size) {
@@ -1703,6 +1709,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
dchunk->map[1] = pcpu_reserved_chunk_limit;
dchunk->map[2] = (pcpu_reserved_chunk_limit + dchunk->free_size) | 1;
dchunk->map_used = 2;
+ dchunk->has_reserved = true;
}
/* link the first chunk in */
@@ -1711,6 +1718,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_count_occupied_pages(pcpu_first_chunk, 1);
pcpu_chunk_relocate(pcpu_first_chunk, -1);
+ pcpu_stats_chunk_alloc();
+
/* we're done */
pcpu_base_addr = base_addr;
return 0;