Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup
On Thu, 2008-02-21 at 11:48 -0500, Steven Rostedt wrote: > On Thu, 21 Feb 2008, Gregory Haskins wrote: > > > From: Peter W.Morreale <[EMAIL PROTECTED]> > > > > In wakeup_next_waiter(), we take the pi_lock, and then find out whether > > we have another waiter to add to the pending owner. We can reduce > > contention on the pi_lock for the pending owner if we first obtain the > > pointer to the next waiter outside of the pi_lock. > > > > This patch adds a measureable increase in throughput. > > I see how this may decrease contention (slightly less time in holding the > pi_lock). But, please, when stating something like: "adds a measurable > increase in throughput", show the benchmark numbers. > > -- Steve > Approximately 3% to the dbench benchmark we used. My "standard" sanity check was to mount a ramfs filesystem and execute: dbench -t 10 30 five times and generate an average from the reported "Throughput" numbers displayed by the runs. dbench was chosen merely because of the contention on dcache_lock. Best, -PWM -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup
On Thu, 21 Feb 2008, Gregory Haskins wrote: > From: Peter W.Morreale <[EMAIL PROTECTED]> > > In wakeup_next_waiter(), we take the pi_lock, and then find out whether > we have another waiter to add to the pending owner. We can reduce > contention on the pi_lock for the pending owner if we first obtain the > pointer to the next waiter outside of the pi_lock. > > This patch adds a measureable increase in throughput. I see how this may decrease contention (slightly less time in holding the pi_lock). But, please, when stating something like: "adds a measurable increase in throughput", show the benchmark numbers. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH [RT] 10/14] adjust pi_lock usage in wakeup
From: Peter W.Morreale <[EMAIL PROTECTED]>
In wakeup_next_waiter(), we take the pi_lock, and then find out whether
we have another waiter to add to the pending owner. We can reduce
contention on the pi_lock for the pending owner if we first obtain the
pointer to the next waiter outside of the pi_lock.
This patch adds a measureable increase in throughput.
Signed-off-by: Peter W. Morreale <[EMAIL PROTECTED]>
---
kernel/rtmutex.c | 14 +-
1 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index a7ed7b2..122f143 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -505,6 +505,7 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
{
struct rt_mutex_waiter *waiter;
struct task_struct *pendowner;
+ struct rt_mutex_waiter *next;
spin_lock(>pi_lock);
@@ -549,6 +550,12 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
* waiter with higher priority than pending-owner->normal_prio
* is blocked on the unboosted (pending) owner.
*/
+
+ if (rt_mutex_has_waiters(lock))
+ next = rt_mutex_top_waiter(lock);
+ else
+ next = NULL;
+
spin_lock(>pi_lock);
WARN_ON(!pendowner->pi_blocked_on);
@@ -557,12 +564,9 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
pendowner->pi_blocked_on = NULL;
- if (rt_mutex_has_waiters(lock)) {
- struct rt_mutex_waiter *next;
-
- next = rt_mutex_top_waiter(lock);
+ if (next)
plist_add(>pi_list_entry, >pi_waiters);
- }
+
spin_unlock(>pi_lock);
}
--
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[PATCH [RT] 10/14] adjust pi_lock usage in wakeup
From: Peter W.Morreale [EMAIL PROTECTED]
In wakeup_next_waiter(), we take the pi_lock, and then find out whether
we have another waiter to add to the pending owner. We can reduce
contention on the pi_lock for the pending owner if we first obtain the
pointer to the next waiter outside of the pi_lock.
This patch adds a measureable increase in throughput.
Signed-off-by: Peter W. Morreale [EMAIL PROTECTED]
---
kernel/rtmutex.c | 14 +-
1 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index a7ed7b2..122f143 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -505,6 +505,7 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
{
struct rt_mutex_waiter *waiter;
struct task_struct *pendowner;
+ struct rt_mutex_waiter *next;
spin_lock(current-pi_lock);
@@ -549,6 +550,12 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
* waiter with higher priority than pending-owner-normal_prio
* is blocked on the unboosted (pending) owner.
*/
+
+ if (rt_mutex_has_waiters(lock))
+ next = rt_mutex_top_waiter(lock);
+ else
+ next = NULL;
+
spin_lock(pendowner-pi_lock);
WARN_ON(!pendowner-pi_blocked_on);
@@ -557,12 +564,9 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int
savestate)
pendowner-pi_blocked_on = NULL;
- if (rt_mutex_has_waiters(lock)) {
- struct rt_mutex_waiter *next;
-
- next = rt_mutex_top_waiter(lock);
+ if (next)
plist_add(next-pi_list_entry, pendowner-pi_waiters);
- }
+
spin_unlock(pendowner-pi_lock);
}
--
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup
On Thu, 2008-02-21 at 11:48 -0500, Steven Rostedt wrote: On Thu, 21 Feb 2008, Gregory Haskins wrote: From: Peter W.Morreale [EMAIL PROTECTED] In wakeup_next_waiter(), we take the pi_lock, and then find out whether we have another waiter to add to the pending owner. We can reduce contention on the pi_lock for the pending owner if we first obtain the pointer to the next waiter outside of the pi_lock. This patch adds a measureable increase in throughput. I see how this may decrease contention (slightly less time in holding the pi_lock). But, please, when stating something like: adds a measurable increase in throughput, show the benchmark numbers. -- Steve Approximately 3% to the dbench benchmark we used. My standard sanity check was to mount a ramfs filesystem and execute: dbench -t 10 30 five times and generate an average from the reported Throughput numbers displayed by the runs. dbench was chosen merely because of the contention on dcache_lock. Best, -PWM -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup
On Thu, 21 Feb 2008, Gregory Haskins wrote: From: Peter W.Morreale [EMAIL PROTECTED] In wakeup_next_waiter(), we take the pi_lock, and then find out whether we have another waiter to add to the pending owner. We can reduce contention on the pi_lock for the pending owner if we first obtain the pointer to the next waiter outside of the pi_lock. This patch adds a measureable increase in throughput. I see how this may decrease contention (slightly less time in holding the pi_lock). But, please, when stating something like: adds a measurable increase in throughput, show the benchmark numbers. -- Steve -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
