[PATCH] percpu: improve percpu_alloc_percpu event trace

Vasily Averin
2022-05-06T04:46:19Z

Added bytes_alloc and gfp_flags fields to the output of the
percpu_alloc_percpu ftrace event. This is required to track
memcg-accounted percpu allocations.

Signed-off-by: Vasily Averin <vvs@openvz.org>
---
include/trace/events/percpu.h | 17 ++++++++++++-----
mm/percpu-internal.h | 8 ++++----
mm/percpu.c | 3 ++-
3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/include/trace/events/percpu.h b/include/trace/events/percpu.h
index df112a64f6c9..a6d640d2cb8b 100644
--- a/include/trace/events/percpu.h
+++ b/include/trace/events/percpu.h
@@ -6,13 +6,16 @@
#define _TRACE_PERCPU_H

#include <linux/tracepoint.h>
+#include <trace/events/mmflags.h>

TRACE_EVENT(percpu_alloc_percpu,

TP_PROTO(bool reserved, bool is_atomic, size_t size,
- size_t align, void *base_addr, int off, void __percpu *ptr),
+ size_t align, void *base_addr, int off,
+ void __percpu *ptr, size_t bytes_alloc, gfp_t gfp_flags),

- TP_ARGS(reserved, is_atomic, size, align, base_addr, off, ptr),
+ TP_ARGS(reserved, is_atomic, size, align, base_addr, off, ptr,
+ bytes_alloc, gfp_flags),

TP_STRUCT__entry(
__field( bool, reserved )
@@ -22,8 +25,9 @@ TRACE_EVENT(percpu_alloc_percpu,
__field( void *, base_addr )
__field( int, off )
__field( void __percpu *, ptr )
+ __field( size_t, bytes_alloc )
+ __field( gfp_t, gfp_flags )
),
-
TP_fast_assign(
__entry->reserved = reserved;
__entry->is_atomic = is_atomic;
@@ -32,12 +36,15 @@ TRACE_EVENT(percpu_alloc_percpu,
__entry->base_addr = base_addr;
__entry->off = off;
__entry->ptr = ptr;
+ __entry->bytes_alloc = bytes_alloc;
+ __entry->gfp_flags = gfp_flags;
),

- TP_printk("reserved=%d is_atomic=%d size=%zu align=%zu base_addr=%p off=%d ptr=%p",
+ TP_printk("reserved=%d is_atomic=%d size=%zu align=%zu base_addr=%p off=%d ptr=%p bytes_alloc=%zu gfp_flags=%s",
__entry->reserved, __entry->is_atomic,
__entry->size, __entry->align,
- __entry->base_addr, __entry->off, __entry->ptr)
+ __entry->base_addr, __entry->off, __entry->ptr,
+ __entry->bytes_alloc, show_gfp_flags(__entry->gfp_flags))
);

TRACE_EVENT(percpu_free_percpu,
diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index 411d1593ef23..70b1ea23f4d2 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -113,7 +113,6 @@ static inline int pcpu_chunk_map_bits(struct pcpu_chunk *chunk)
return pcpu_nr_pages_to_map_bits(chunk->nr_pages);
}

-#ifdef CONFIG_MEMCG_KMEM
/**
* pcpu_obj_full_size - helper to calculate size of each accounted object
* @size: size of area to allocate in bytes
@@ -123,13 +122,14 @@ static inline int pcpu_chunk_map_bits(struct pcpu_chunk *chunk)
*/
static inline size_t pcpu_obj_full_size(size_t size)
{
- size_t extra_size;
+ size_t extra_size = 0;

- extra_size = size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *);
+#ifdef CONFIG_MEMCG_KMEM
+ extra_size += size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *);
+#endif

return size * num_possible_cpus() + extra_size;
}
-#endif /* CONFIG_MEMCG_KMEM */

#ifdef CONFIG_PERCPU_STATS

diff --git a/mm/percpu.c b/mm/percpu.c
index ea28db283044..cbeb380c359d 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1885,7 +1885,8 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
kmemleak_alloc_percpu(ptr, size, gfp);

trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
- chunk->base_addr, off, ptr);
+ chunk->base_addr, off, ptr,
+ pcpu_obj_full_size(size), gfp);

pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);

--
2.31.1