[PATCH v2 4/7] mmap_lock: allocate histogram (if enabled) in mm_init

* [PATCH v2 4/7] mmap_lock: allocate histogram (if enabled) in mm_init
@ 2020-05-28 23:53 Axel Rasmussen
  0 siblings, 0 replies; only message in thread
From: Axel Rasmussen @ 2020-05-28 23:53 UTC (permalink / raw)
  To: Andrew Morton, David Rientjes, Davidlohr Bueso, Ingo Molnar,
	Ingo Molnar, Jerome Glisse, Laurent Dufour, Liam R . Howlett,
	Matthew Wilcox, Michel Lespinasse, Peter Zijlstra,
	Vlastimil Babka, Will Deacon
  Cc: linux-fsdevel, linux-kernel, linux-mm, AKASHI Takahiro,
	Aleksa Sarai, Alexander Potapenko, Alexey Dobriyan, Al Viro,
	Andrei Vagin, Ard Biesheuvel, Brendan Higgins, chenqiwu,
	Christian Brauner, Christian Kellner, Corentin Labbe,
	Daniel Jordan, Dan Williams, David Gow, David S. Miller,
	Dmitry V. Levin, Eric W. Biederman, Eugene Syromiatnikov,
	Jamie Liu, Jason Gunthorpe, John Garry, John Hubbard,
	Jonathan Adams, Junaid Shahid, Kees Cook, Kirill A. Shutemov,
	Konstantin Khlebnikov, Krzysztof Kozlowski, Mark Rutland,
	Masahiro Yamada, Masami Hiramatsu, Mathieu Desnoyers,
	Michal Hocko, Mikhail Zaslonko, Petr Mladek, Ralph Campbell,
	Randy Dunlap, Roman Gushchin, Shakeel Butt, Steven Rostedt,
	Tal Gilboa, Thomas Gleixner, Uwe Kleine-König,
	Vincenzo Frascino, Yang Shi, Yu Zhao, Axel Rasmussen

In effect, allocate a histogram for each process. On fork, initialize a
new empty histogram (don't keep recorded samples from the parent).

Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
---
 kernel/fork.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index e702e84897fa..afb036d81a73 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -94,6 +94,7 @@
 #include <linux/thread_info.h>
 #include <linux/stackleak.h>
 #include <linux/kasan.h>
+#include <linux/histogram.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -975,6 +976,58 @@ __setup("coredump_filter=", coredump_filter_setup);
 
 #include <linux/init_task.h>
 
+#ifdef CONFIG_MMAP_LOCK_HISTOGRAMS
+static const u64 mmap_lock_contention_buckets[] = {
+	1,		/* 0ns - uncontended acquisitions */
+	250,		/* 250 ns */
+	375,		/* 375 ns */
+	500,		/* 500 ns */
+	1000,		/* 1 us */
+	10000,		/* 10 us */
+	100000,		/* 100 us */
+	500000,		/* 500 us */
+	1000000,	/* 1 ms */
+	5000000,	/* 5 ms */
+	10000000,	/* 10 ms */
+	50000000,	/* 50 ms */
+	100000000,	/* 100 ms */
+	500000000,	/* 500 ms */
+	1000000000,	/* 1 s */
+	5000000000UL,	/* 5 s */
+	10000000000UL,	/* 10 s */
+	~0		/* > 10s */
+};
+#endif
+
+static void mm_init_histograms(struct mm_struct *mm)
+{
+#ifdef CONFIG_MMAP_LOCK_HISTOGRAMS
+	mm->mmap_lock_contention =
+		kmalloc(sizeof(struct histogram_rcu), GFP_KERNEL);
+	if (unlikely(!mm->mmap_lock_contention))
+		return;
+
+	if (unlikely(histogram_init_rcu(
+		    mm->mmap_lock_contention, mmap_lock_contention_buckets,
+		    ARRAY_SIZE(mmap_lock_contention_buckets)))) {
+		kfree(mm->mmap_lock_contention);
+		mm->mmap_lock_contention = NULL;
+	}
+#endif
+}
+
+static void mm_free_histograms(struct mm_struct *mm)
+{
+#ifdef CONFIG_MMAP_LOCK_HISTOGRAMS
+	if (unlikely(!mm->mmap_lock_contention))
+		return;
+
+	histogram_destroy_rcu(mm->mmap_lock_contention);
+	kfree(mm->mmap_lock_contention);
+	mm->mmap_lock_contention = NULL;
+#endif
+}
+
 static void mm_init_aio(struct mm_struct *mm)
 {
 #ifdef CONFIG_AIO
@@ -1015,6 +1068,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	atomic_set(&mm->mm_users, 1);
 	atomic_set(&mm->mm_count, 1);
 	mmap_init_lock(mm);
+	mm_init_histograms(mm);
 	INIT_LIST_HEAD(&mm->mmlist);
 	mm->core_state = NULL;
 	mm_pgtables_bytes_init(mm);
@@ -1078,6 +1132,7 @@ static inline void __mmput(struct mm_struct *mm)
 {
 	VM_BUG_ON(atomic_read(&mm->mm_users));
 
+	mm_free_histograms(mm);
 	uprobe_clear_state(mm);
 	exit_aio(mm);
 	ksm_exit(mm);
-- 
2.27.0.rc0.183.gde8f92d652-goog



^ permalink raw reply related	[flat|nested] only message in thread