The patch titled
Subject: debugobjects: track number of kmem_cache_alloc/kmem_cache_free done
has been removed from the -mm tree. Its filename was
debugobjects-track-number-of-kmem_cache_alloc-kmem_cache_free-done.patch
This patch was dropped because an alternative patch was merged
------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: debugobjects: track number of kmem_cache_alloc/kmem_cache_free done
Patch series "debugobjects: Reduce global pool_lock contention", v2.
This patchset aims to reduce contention of the global pool_lock while
improving performance at the same time. It is done to resolve the
following soft lockup problem with a debug kernel in some of the large SMP
systems:
NMI watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [rcuos/1:21]
...
RIP: 0010:[<ffffffff817c216b>] [<ffffffff817c216b>]
_raw_spin_unlock_irqrestore+0x3b/0x60
...
Call Trace:
[<ffffffff813f40d1>] free_object+0x81/0xb0
[<ffffffff813f4f33>] debug_check_no_obj_freed+0x193/0x220
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff81284996>] ? file_free_rcu+0x36/0x60
[<ffffffff81251712>] kmem_cache_free+0xd2/0x380
[<ffffffff81284960>] ? fput+0x90/0x90
[<ffffffff81284996>] file_free_rcu+0x36/0x60
[<ffffffff81124c23>] rcu_nocb_kthread+0x1b3/0x550
[<ffffffff81124b71>] ? rcu_nocb_kthread+0x101/0x550
[<ffffffff81124a70>] ? sync_exp_work_done.constprop.63+0x50/0x50
[<ffffffff810c59d1>] kthread+0x101/0x120
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff817c2d32>] ret_from_fork+0x22/0x50
On a 8-socket IvyBridge-EX system (120 cores, 240 threads), the elapsed
time of a 4.9-rc7 kernel parallel build (make -j 240) was reduced from
7m57s to 7m19s with a patched 4.9-rc7 kernel. There was also about a 10X
reduction in the number of debug objects being allocated from or freed to
the kmemcache during the kernel build.
This patch (of 3):
New debugfs stat counters are added to track the numbers of
kmem_cache_alloc() and kmem_cache_free() function calls to get a sense of
how the internal debug objects cache management is performing.
Link: http://lkml.kernel.org/r/1483647425-4135-2-git-send-email-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "Du Changbin" <changbin.du@xxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Jan Stancek <jstancek@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/debugobjects.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff -puN lib/debugobjects.c~debugobjects-track-number-of-kmem_cache_alloc-kmem_cache_free-done lib/debugobjects.c
--- a/lib/debugobjects.c~debugobjects-track-number-of-kmem_cache_alloc-kmem_cache_free-done
+++ a/lib/debugobjects.c
@@ -55,6 +55,12 @@ static int debug_objects_enabled __rea
static struct debug_obj_descr *descr_test __read_mostly;
+/*
+ * Track numbers of kmem_cache_alloc and kmem_cache_free done.
+ */
+static int debug_objects_alloc;
+static int debug_objects_freed;
+
static void free_obj_work(struct work_struct *work);
static DECLARE_WORK(debug_obj_work, free_obj_work);
@@ -102,6 +108,7 @@ static void fill_pool(void)
raw_spin_lock_irqsave(&pool_lock, flags);
hlist_add_head(&new->node, &obj_pool);
+ debug_objects_alloc++;
obj_pool_free++;
raw_spin_unlock_irqrestore(&pool_lock, flags);
}
@@ -173,6 +180,7 @@ static void free_obj_work(struct work_st
obj = hlist_entry(obj_pool.first, typeof(*obj), node);
hlist_del(&obj->node);
obj_pool_free--;
+ debug_objects_freed++;
/*
* We release pool_lock across kmem_cache_free() to
* avoid contention on pool_lock.
@@ -758,6 +766,8 @@ static int debug_stats_show(struct seq_f
seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);
seq_printf(m, "pool_used :%d\n", obj_pool_used);
seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);
+ seq_printf(m, "objects_alloc :%d\n", debug_objects_alloc);
+ seq_printf(m, "objects_freed :%d\n", debug_objects_freed);
return 0;
}
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
debugobjects-scale-thresholds-with-of-cpus.patch
debugobjects-reduce-contention-on-the-global-pool_lock.patch
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