[PATCH v2] lib/alloc_tag: Add accumulative call counter for memory allocation profiling

[David Wang <00107082@163.com>]

Accumulative allocation counter can be used to evaluate
memory allocation behavior/rate via delta(counters)/delta(time).
It can help analysis performance issues, identify top modules
with high rate of memory allocation activity.
Considering this would incur extra performance and memory impact,
introduce kconfig MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER.

Signed-off-by: David Wang <00107082@163.com>
---
Changes in v2:
- Add kconfig MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER as
suggested by "Kent Overstreet <kent.overstreet@linux.dev>"

---
 include/linux/alloc_tag.h | 18 +++++++++++++++---
 lib/Kconfig.debug         | 10 ++++++++++
 lib/alloc_tag.c           | 10 +++++++++-
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
index 8c61ccd161ba..5a94d61205b5 100644
--- a/include/linux/alloc_tag.h
+++ b/include/linux/alloc_tag.h
@@ -18,6 +18,9 @@
 struct alloc_tag_counters {
 	u64 bytes;
 	u64 calls;
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	u64 accu_calls;
+#endif
 };
 
 /*
@@ -103,13 +106,19 @@ static inline bool mem_alloc_profiling_enabled(void)
 static inline struct alloc_tag_counters alloc_tag_read(struct alloc_tag *tag)
 {
 	struct alloc_tag_counters v = { 0, 0 };
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	v.accu_calls = 0;
+#endif
 	struct alloc_tag_counters *counter;
 	int cpu;
 
 	for_each_possible_cpu(cpu) {
-		counter = per_cpu_ptr(tag->counters, cpu);
-		v.bytes += counter->bytes;
-		v.calls += counter->calls;
+		counter		= per_cpu_ptr(tag->counters, cpu);
+		v.bytes		+= counter->bytes;
+		v.calls		+= counter->calls;
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+		v.accu_calls	+= counter->accu_calls;
+#endif
 	}
 
 	return v;
@@ -145,6 +154,9 @@ static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag
 	 * counter because when we free each part the counter will be decremented.
 	 */
 	this_cpu_inc(tag->counters->calls);
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	this_cpu_inc(tag->counters->accu_calls);
+#endif
 }
 
 static inline void alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a30c03a66172..1e9974d28510 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1000,6 +1000,16 @@ config MEM_ALLOC_PROFILING_DEBUG
 	  Adds warnings with helpful error messages for memory allocation
 	  profiling.
 
+config MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	bool "Enable accumulative allocation counters"
+	default n
+	depends on MEM_ALLOC_PROFILING
+	help
+	  Record accumulative call counters for memory allocation. This may have
+	  extra performance and memory impact, but the impact is small.
+	  The stat can be used to evaluate allocation activity/rate
+	  via delta(counter)/delta(time).
+
 source "lib/Kconfig.kasan"
 source "lib/Kconfig.kfence"
 source "lib/Kconfig.kmsan"
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 81e5f9a70f22..6b03edb04e7d 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -66,8 +66,12 @@ static void allocinfo_stop(struct seq_file *m, void *arg)
 static void print_allocinfo_header(struct seq_buf *buf)
 {
 	/* Output format version, so we can change it. */
-	seq_buf_printf(buf, "allocinfo - version: 1.0\n");
+	seq_buf_printf(buf, "allocinfo - version: 1.1\n");
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	seq_buf_printf(buf, "#     <size>  <calls> <tag info> <accumulative calls>\n");
+#else
 	seq_buf_printf(buf, "#     <size>  <calls> <tag info>\n");
+#endif
 }
 
 static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct)
@@ -78,8 +82,12 @@ static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct)
 
 	seq_buf_printf(out, "%12lli %8llu ", bytes, counter.calls);
 	codetag_to_text(out, ct);
+#ifdef CONFIG_MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER
+	seq_buf_printf(out, " %llu\n", counter.accu_calls);
+#else
 	seq_buf_putc(out, ' ');
 	seq_buf_putc(out, '\n');
+#endif
 }
 
 static int allocinfo_show(struct seq_file *m, void *arg)
-- 
2.39.2