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Subject[tip:core/debugobjects] debugobjects: Export max loops counter
Commit-ID:  bd9dcd046509cd5355605e43791eacee8bf5e40f
Gitweb: https://git.kernel.org/tip/bd9dcd046509cd5355605e43791eacee8bf5e40f
Author: Yang Shi <yang.shi@linux.alibaba.com>
AuthorDate: Tue, 6 Feb 2018 07:18:25 +0800
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 13 Feb 2018 10:58:58 +0100

debugobjects: Export max loops counter

__debug_check_no_obj_freed() can be an expensive operation depending on the
size of memory freed. It already exports the maximum chain walk length via
debugfs, but this only records the maximum of a single memory chunk.

Though there is no information about the total number of objects inspected
for a __debug_check_no_obj_freed() operation, which might be significantly
larger when a huge memory region is freed.

Aggregate the number of objects inspected for a single invocation of
__debug_check_no_obj_freed() and export it via sysfs.

The resulting output of /sys/kernel/debug/debug_objects/stats looks like:

max_chain :121
max_checked :543267
warnings :0
fixups :0
pool_free :1764
pool_min_free :341
pool_used :86438
pool_max_used :268887
objs_allocated:6068254
objs_freed :5981076

[ tglx: Renamed the variable to max_checked and adjusted changelog ]

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/1517872708-24207-2-git-send-email-yang.shi@linux.alibaba.com

---
lib/debugobjects.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 2f5349c..f6d57a1 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -50,6 +50,7 @@ static int obj_pool_max_used;
static struct kmem_cache *obj_cache;

static int debug_objects_maxchain __read_mostly;
+static int debug_objects_maxchecked __read_mostly;
static int debug_objects_fixups __read_mostly;
static int debug_objects_warnings __read_mostly;
static int debug_objects_enabled __read_mostly
@@ -720,7 +721,7 @@ static void __debug_check_no_obj_freed(const void *address, unsigned long size)
enum debug_obj_state state;
struct debug_bucket *db;
struct debug_obj *obj;
- int cnt;
+ int cnt, objs_checked = 0;

saddr = (unsigned long) address;
eaddr = saddr + size;
@@ -765,7 +766,12 @@ repeat:

if (cnt > debug_objects_maxchain)
debug_objects_maxchain = cnt;
+
+ objs_checked += cnt;
}
+
+ if (objs_checked > debug_objects_maxchecked)
+ debug_objects_maxchecked = objs_checked;
}

void debug_check_no_obj_freed(const void *address, unsigned long size)
@@ -780,6 +786,7 @@ void debug_check_no_obj_freed(const void *address, unsigned long size)
static int debug_stats_show(struct seq_file *m, void *v)
{
seq_printf(m, "max_chain :%d\n", debug_objects_maxchain);
+ seq_printf(m, "max_checked :%d\n", debug_objects_maxchecked);
seq_printf(m, "warnings :%d\n", debug_objects_warnings);
seq_printf(m, "fixups :%d\n", debug_objects_fixups);
seq_printf(m, "pool_free :%d\n", obj_pool_free);
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