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Date: Wed, 20 Aug 2008 17:02:21 -0700
From: Jeremy Fitzhardinge <jeremy@...p.org>
To: Ingo Molnar <mingo@...e.hu>
Cc: linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
Jan Beulich <jbeulich@...ell.com>
Subject: [PATCH 4 of 4] xen: measure how long spinlocks spend blocking
Measure how long spinlocks spend blocked. Also rename some fields to
be more consistent.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
arch/x86/xen/spinlock.c | 60 ++++++++++++++++++++++++++++++++---------------
1 file changed, 41 insertions(+), 19 deletions(-)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -29,12 +29,14 @@
u32 released_slow;
u32 released_slow_kicked;
-#define HISTO_BUCKETS 20
- u32 histo_spin_fast[HISTO_BUCKETS+1];
- u32 histo_spin[HISTO_BUCKETS+1];
+#define HISTO_BUCKETS 30
+ u32 histo_spin_total[HISTO_BUCKETS+1];
+ u32 histo_spin_spinning[HISTO_BUCKETS+1];
+ u32 histo_spin_blocked[HISTO_BUCKETS+1];
- u64 spinning_time;
- u64 total_time;
+ u64 time_total;
+ u64 time_spinning;
+ u64 time_blocked;
} spinlock_stats;
static u8 zero_stats;
@@ -70,20 +72,28 @@
array[HISTO_BUCKETS]++;
}
-static inline void spin_time_accum_fast(u64 start)
+static inline void spin_time_accum_spinning(u64 start)
{
u32 delta = xen_clocksource_read() - start;
- __spin_time_accum(delta, spinlock_stats.histo_spin_fast);
- spinlock_stats.spinning_time += delta;
+ __spin_time_accum(delta, spinlock_stats.histo_spin_spinning);
+ spinlock_stats.time_spinning += delta;
}
-static inline void spin_time_accum(u64 start)
+static inline void spin_time_accum_total(u64 start)
{
u32 delta = xen_clocksource_read() - start;
- __spin_time_accum(delta, spinlock_stats.histo_spin);
- spinlock_stats.total_time += delta;
+ __spin_time_accum(delta, spinlock_stats.histo_spin_total);
+ spinlock_stats.time_total += delta;
+}
+
+static inline void spin_time_accum_blocked(u64 start)
+{
+ u32 delta = xen_clocksource_read() - start;
+
+ __spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
+ spinlock_stats.time_blocked += delta;
}
#else /* !CONFIG_XEN_DEBUG_FS */
#define TIMEOUT (1 << 10)
@@ -94,10 +104,13 @@
return 0;
}
-static inline void spin_time_accum_fast(u64 start)
+static inline void spin_time_accum_total(u64 start)
{
}
-static inline void spin_time_accum(u64 start)
+static inline void spin_time_accum_spinning(u64 start)
+{
+}
+static inline void spin_time_accum_blocked(u64 start)
{
}
#endif /* CONFIG_XEN_DEBUG_FS */
@@ -175,10 +188,13 @@
int irq = __get_cpu_var(lock_kicker_irq);
int ret;
unsigned long flags;
+ u64 start;
/* If kicker interrupts not initialized yet, just spin */
if (irq == -1)
return 0;
+
+ start = spin_time_start();
/* announce we're spinning */
prev = spinning_lock(xl);
@@ -230,6 +246,8 @@
out:
raw_local_irq_restore(flags);
unspinning_lock(xl, prev);
+ spin_time_accum_blocked(start);
+
return ret;
}
@@ -262,12 +280,12 @@
: "1" (1)
: "memory");
- spin_time_accum_fast(start_spin_fast);
+ spin_time_accum_spinning(start_spin_fast);
} while (unlikely(oldval != 0 &&
(TIMEOUT == ~0 || !xen_spin_lock_slow(lock, irq_enable))));
- spin_time_accum(start_spin);
+ spin_time_accum_total(start_spin);
}
static void xen_spin_lock(struct raw_spinlock *lock)
@@ -385,14 +403,18 @@
&spinlock_stats.released_slow_kicked);
debugfs_create_u64("time_spinning", 0444, d_spin_debug,
- &spinlock_stats.spinning_time);
+ &spinlock_stats.time_spinning);
+ debugfs_create_u64("time_blocked", 0444, d_spin_debug,
+ &spinlock_stats.time_blocked);
debugfs_create_u64("time_total", 0444, d_spin_debug,
- &spinlock_stats.total_time);
+ &spinlock_stats.time_total);
xen_debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
- spinlock_stats.histo_spin, HISTO_BUCKETS + 1);
+ spinlock_stats.histo_spin_total, HISTO_BUCKETS + 1);
xen_debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
- spinlock_stats.histo_spin_fast, HISTO_BUCKETS + 1);
+ spinlock_stats.histo_spin_spinning, HISTO_BUCKETS + 1);
+ xen_debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
+ spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
return 0;
}
--
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