From: Axel Rasmussen <axelrasmussen@google.com>
To: Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Davidlohr Bueso <dbueso@suse.de>, Ingo Molnar <mingo@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
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Laurent Dufour <ldufour@linux.ibm.com>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
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Michel Lespinasse <walken@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Will Deacon <will@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
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"AKASHI Takahiro" <takahiro.akashi@linaro.org>,
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"Mikhail Zaslonko" <zaslonko@linux.ibm.com>,
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"Axel Rasmussen" <axelrasmussen@google.com>
Subject: [PATCH v2 4/7] mmap_lock: allocate histogram (if enabled) in mm_init
Date: Thu, 28 May 2020 16:53:00 -0700 [thread overview]
Message-ID: <20200528235300.77135-1-axelrasmussen@google.com> (raw)
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
reply other threads:[~2020-05-28 23:53 UTC|newest]
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