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Message-ID: <710f85e7.a802.193d9d08d8a.Coremail.00107082@163.com>
Date: Wed, 18 Dec 2024 20:49:03 +0800 (CST)
From: "David Wang" <00107082@....com>
To: surenb@...gle.com, kent.overstreet@...ux.dev, akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re:[PATCH v2] lib/alloc_tag: Add accumulative call counter for
memory allocation profiling
Hi,
I found another usage/benefit for accumulative counters:
On my system, /proc/allocinfo yields about 5065 lines, of which 2/3 lines have accumulative counter *0*.
meaning no memory activities. (right?)
It is quite a waste to keep those items which are *not alive yet*.
With additional changes, only 1684 lines in /proc/allocinfo on my system:
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -95,8 +95,11 @@ static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct)
struct alloc_tag_counters counter = alloc_tag_read(tag);
s64 bytes = counter.bytes;
+ if (counter.accu_calls == 0)
+ return;
seq_buf_printf(out, "%12lli %8llu ", bytes, counter.calls);
I think this is quite an improvement worth pursuing.
(counter.calls could also be used to filter out "inactive" items, but
lines keep disappearing/reappearing can confuse monitoring systems.)
Thanks~
David
At 2024-09-13 13:57:29, "David Wang" <00107082@....com> wrote:
>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@....com>
>---
>Changes in v2:
>- Add kconfig MEM_ALLOC_PROFILING_ACCUMULATIVE_CALL_COUNTER as
>suggested by "Kent Overstreet <kent.overstreet@...ux.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
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