On 04/04/2014 12:57 PM, Konrad Rzeszutek Wilk wrote:
On Fri, Apr 04, 2014 at 03:00:12PM +0200, Peter Zijlstra wrote:
So I'm just not ever going to pick up this patch; I spend a week trying
to reverse engineer this; I posted a 7 patch series creating the
equivalent, but in a gradual and readable
On 04/04/2014 12:55 PM, Konrad Rzeszutek Wilk wrote:
On Thu, Apr 03, 2014 at 10:57:18PM -0400, Waiman Long wrote:
On 04/03/2014 01:23 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Apr 02, 2014 at 10:10:17PM -0400, Waiman Long wrote:
On 04/02/2014 04:35 PM, Waiman Long wrote:
On 04/02/2014 10:32
On 04/03/2014 01:23 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Apr 02, 2014 at 10:10:17PM -0400, Waiman Long wrote:
On 04/02/2014 04:35 PM, Waiman Long wrote:
On 04/02/2014 10:32 AM, Konrad Rzeszutek Wilk wrote:
On Wed, Apr 02, 2014 at 09:27:29AM -0400, Waiman Long wrote:
N.B. Sorry
optimization which will make the queue spinlock code perform
better than the generic implementation.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
arch/x86/Kconfig |1 +
arch/x86/include/asm/qspinlock.h | 41
now be defined in an architecture specific qspinlock.h header
file to indicate its support for smaller atomic operation data types.
This macro triggers the replacement of some of the generic functions
by more optimized versions.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include
Westmere-EP (HT on)
Waiman Long (10):
qspinlock: A generic 4-byte queue spinlock implementation
qspinlock, x86: Enable x86-64 to use queue spinlock
qspinlock: More optimized code for smaller NR_CPUS
qspinlock: Optimized code path for 2 contending tasks
pvqspinlock, x86: Allow unfair spinlock
benefit of an unfair lock. For large critical section,
however, there may not be much benefit.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/Kconfig | 11
arch/x86/include/asm/qspinlock.h | 86 +-
arch/x86/kernel/Makefile
. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 +++
include/asm-generic/qspinlock_types.h | 49 +
kernel/Kconfig.locks
7641 -15%
7 12907 8373 -35%
8 15094 10259 -32%
There is some performance drop at the 3 contending tasks level.
Other than that, queue spinlock is faster than ticket spinlock.
Signed-off-by: Waiman Long waiman.l
2732 4653
Signed-off-by: Waiman Long waiman.l...@hp.com
---
kernel/locking/qspinlock.c | 270 +++-
1 files changed, 265 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index cf16bba..527efc3
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/spinlock.h |4 ++--
arch/x86/kernel/kvm.c|2 +-
arch/x86/kernel/paravirt
-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 111 +
kernel/Kconfig.locks |2 +-
2 files changed, 112 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 8e646a7..7d97e58 100644
the unfair lock and PV spinlock features is turned on,
lock stealing will still be allowed in the fastpath, but not in
the slowpath.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/paravirt.h | 17 ++-
arch/x86/include/asm/paravirt_types.h | 16 ++
arch/x86/include/asm
This patch adds the necessary KVM specific code to allow XEN to support
the sleeping and CPU kicking operations needed by the queue spinlock PV
code.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/xen/spinlock.c | 119 +--
kernel
On 04/02/2014 10:32 AM, Konrad Rzeszutek Wilk wrote:
On Wed, Apr 02, 2014 at 09:27:29AM -0400, Waiman Long wrote:
N.B. Sorry for the duplicate. This patch series were resent as the
original one was rejected by the vger.kernel.org list server
due to long header. There is no change
On 04/02/2014 10:39 AM, Konrad Rzeszutek Wilk wrote:
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index a70fdeb..451e392 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK
config QUEUE_SPINLOCK
def_bool y if
optimization which will make the queue spinlock code perform
better than the generic implementation.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
arch/x86/Kconfig |1 +
arch/x86/include/asm/qspinlock.h | 41
2899 rec/s
Westmere-EX (HT off)
2-socket 12-core 2130 rec/s 2176 rec/s
Westmere-EP (HT on)
Waiman Long (10):
qspinlock: A generic 4-byte queue spinlock implementation
qspinlock, x86: Enable x86-64 to use queue spinlock
qspinlock: More optimized code
now be defined in an architecture specific qspinlock.h header
file to indicate its support for smaller atomic operation data types.
This macro triggers the replacement of some of the generic functions
by more optimized versions.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include
benefit of an unfair lock. For large critical section,
however, there may not be much benefit.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/Kconfig | 11
arch/x86/include/asm/qspinlock.h | 86 +-
arch/x86/kernel/Makefile
2732 4653
Signed-off-by: Waiman Long waiman.l...@hp.com
---
kernel/locking/qspinlock.c | 270 +++-
1 files changed, 265 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index cf16bba..527efc3
7641 -15%
7 12907 8373 -35%
8 15094 10259 -32%
There is some performance drop at the 3 contending tasks level.
Other than that, queue spinlock is faster than ticket spinlock.
Signed-off-by: Waiman Long waiman.l
. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 +++
include/asm-generic/qspinlock_types.h | 49 +
kernel/Kconfig.locks
-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 111 +
kernel/Kconfig.locks |2 +-
2 files changed, 112 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 8e646a7..7d97e58 100644
the unfair lock and PV spinlock features is turned on,
lock stealing will still be allowed in the fastpath, but not in
the slowpath.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/paravirt.h | 17 ++-
arch/x86/include/asm/paravirt_types.h | 16 ++
arch/x86/include/asm
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/spinlock.h |4 ++--
arch/x86/kernel/kvm.c|2 +-
arch/x86/kernel/paravirt
On 03/20/2014 06:01 PM, Paolo Bonzini wrote:
Il 19/03/2014 21:14, Waiman Long ha scritto:
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
On 03/20/2014 06:07 PM, Paolo Bonzini wrote:
Il 19/03/2014 21:14, Waiman Long ha scritto:
This patch adds the necessary KVM specific code to allow KVM to support
the sleeping and CPU kicking operations needed by the queue spinlock PV
code.
The remaining problem of this patch is that you
On 03/19/2014 04:24 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Mar 19, 2014 at 04:14:00PM -0400, Waiman Long wrote:
This patch makes the necessary changes at the x86 architecture
specific layer to enable the use of queue spinlock for x86-64. As
x86-32 machines are typically not multi-socket
On 03/19/2014 04:28 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Mar 19, 2014 at 04:14:05PM -0400, Waiman Long wrote:
This patch adds a XEN init function to activate the unfair queue
spinlock in a XEN guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman
On 03/19/2014 06:07 AM, Paolo Bonzini wrote:
Il 19/03/2014 04:15, Waiman Long ha scritto:
You should see the same values with the PV ticketlock. It is not clear
to me if this testing did include that variant of locks?
Yes, PV is fine. But up to this point of the series, we are concerned
. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 +++
include/asm-generic/qspinlock_types.h | 49 +
kernel/Kconfig.locks
now be defined in an architecture specific qspinlock.h header
file to indicate its support for smaller atomic operation data types.
This macro triggers the replacement of some of the generic functions
by more optimized versions.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include
individual task. For the 4 nodes case above,
the standard deviation was 785ms.
In general, the shorter the critical section, the better the
performance benefit of an unfair lock. For large critical section,
however, there may not be much benefit.
Signed-off-by: Waiman Long waiman.l...@hp.com
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/spinlock.h |4 ++--
arch/x86/kernel/kvm.c|2 +-
arch/x86/kernel/paravirt
This patch adds a XEN init function to activate the unfair queue
spinlock in a XEN guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/xen/setup.c | 19 +++
1 files changed, 19 insertions(+), 0
in performance. When coupled
with unfair lock, the queue spinlock can be much faster than the PV
ticket lock.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/paravirt.h | 12 ++-
arch/x86/include/asm/paravirt_types.h |5 +
arch/x86/include/asm/pvqspinlock.h
cases, especially with heavy spinlock contention.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 82 +
kernel/Kconfig.locks |2 +-
2 files changed, 83 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c
This patch adds the necessary KVM specific code to allow XEN to support
the sleeping and CPU kicking operations needed by the queue spinlock PV
code.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/xen/spinlock.c | 90 ---
kernel
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 17 +
1 files changed, 17 insertions(+), 0
. The
main purpose is to make the lock contention problems more tolerable
until someone can spend the time and effort to fix them.
Waiman Long (11):
qspinlock: A generic 4-byte queue spinlock implementation
qspinlock, x86: Enable x86-64 to use queue spinlock
qspinlock: More optimized code
optimization which will make the queue spinlock code perform
better than the generic implementation.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
arch/x86/Kconfig |1 +
arch/x86/include/asm/qspinlock.h | 41
10796 -48%
Except some drop in performance at the 3 contending tasks level,
the queue spinlock performs much better than the ticket spinlock at
2 and 4 contending tasks level.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/qspinlock.h |3 +-
kernel
On 03/17/2014 02:54 PM, Peter Zijlstra wrote:
On Mon, Mar 17, 2014 at 01:44:34PM -0400, Waiman Long wrote:
The PV ticketlock code was designed to handle lock holder preemption by
redirecting CPU resources in a preempted guest to another guest that can
better use it and then return the preempted
On 03/17/2014 03:10 PM, Konrad Rzeszutek Wilk wrote:
On Mon, Mar 17, 2014 at 01:44:34PM -0400, Waiman Long wrote:
On 03/14/2014 04:30 AM, Peter Zijlstra wrote:
On Thu, Mar 13, 2014 at 04:05:19PM -0400, Waiman Long wrote:
On 03/13/2014 11:15 AM, Peter Zijlstra wrote:
On Wed, Mar 12, 2014
On 03/18/2014 04:14 AM, Paolo Bonzini wrote:
Il 17/03/2014 20:05, Konrad Rzeszutek Wilk ha scritto:
Measurements were done by Gleb for two guests running 2.6.32 with 16
vcpus each, on a 16-core system. One guest ran with unfair locks,
one guest ran with fair locks. Two kernel compilations
On 03/13/2014 09:57 AM, Peter Zijlstra wrote:
On Wed, Mar 12, 2014 at 03:08:24PM -0400, Waiman Long wrote:
On 03/12/2014 02:54 PM, Waiman Long wrote:
+ /*
+* Set the lock bit clear the waiting bit simultaneously
+* It is assumed
On 03/14/2014 04:30 AM, Peter Zijlstra wrote:
On Thu, Mar 13, 2014 at 04:05:19PM -0400, Waiman Long wrote:
On 03/13/2014 11:15 AM, Peter Zijlstra wrote:
On Wed, Mar 12, 2014 at 02:54:52PM -0400, Waiman Long wrote:
+static inline void arch_spin_lock(struct qspinlock *lock
On 03/14/2014 04:42 AM, Paolo Bonzini wrote:
Il 13/03/2014 20:13, Waiman Long ha scritto:
This should also disable the unfair path.
Paolo
The unfair lock uses a different jump label and does not require any
special PV ops. There is a separate init function for that.
Yeah, what I mean
On 03/13/2014 06:54 AM, David Vrabel wrote:
On 12/03/14 18:54, Waiman Long wrote:
Locking is always an issue in a virtualized environment as the virtual
CPU that is waiting on a lock may get scheduled out and hence block
any progress in lock acquisition even when the lock has been freed.
One
On 03/13/2014 07:21 AM, David Vrabel wrote:
On 12/03/14 18:54, Waiman Long wrote:
This patch adds para-virtualization support to the queue spinlock in
the same way as was done in the PV ticket lock code. In essence, the
lock waiters will spin for a specified number of times (QSPIN_THRESHOLD
= 2
On 03/13/2014 09:57 AM, Paolo Bonzini wrote:
Il 13/03/2014 12:21, David Vrabel ha scritto:
On 12/03/14 18:54, Waiman Long wrote:
This patch adds para-virtualization support to the queue spinlock in
the same way as was done in the PV ticket lock code. In essence, the
lock waiters will spin
On 03/13/2014 11:15 AM, Peter Zijlstra wrote:
On Wed, Mar 12, 2014 at 02:54:52PM -0400, Waiman Long wrote:
+static inline void arch_spin_lock(struct qspinlock *lock)
+{
+ if (static_key_false(paravirt_unfairlocks_enabled))
+ queue_spin_lock_unfair(lock);
+ else
On 03/13/2014 11:25 AM, Peter Zijlstra wrote:
On Wed, Mar 12, 2014 at 02:54:57PM -0400, Waiman Long wrote:
A KVM guest of 20 CPU cores was created to run the disk workload of
the AIM7 benchmark on both ext4 and xfs RAM disks at 3000 users on a
3.14-rc6 based kernel. The JPM (jobs/minute) data
spinlock
contention problems. Those need to be solved by refactoring the code
to make more efficient use of the lock or finer granularity ones. The
main purpose is to make the lock contention problems more tolerable
until someone can spend the time and effort to fix them.
Waiman Long (11):
qspinlock
. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 +++
include/asm-generic/qspinlock_types.h | 55 +
kernel/Kconfig.locks
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 17 +
1 files changed, 17 insertions(+), 0
10796 -48%
Except some drop in performance at the 3 contending tasks level,
the queue spinlock performs much better than the ticket spinlock at
2 and 4 contending tasks level.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/qspinlock.h |3 +-
kernel
This patch adds a XEN init function to activate the unfair queue
spinlock in a XEN guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/xen/setup.c | 19 +++
1 files changed, 19 insertions(+), 0
section, the better the
performance benefit of an unfair lock. For large critical section,
however, there may not be much benefit.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/Kconfig | 11 +
arch/x86/include/asm/qspinlock.h | 72
now be defined in an architecture specific qspinlock.h header
file to indicate its support for smaller atomic operation data types.
This macro triggers the replacement of some of the generic functions
by more optimized versions.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/spinlock.h |4 ++--
arch/x86/kernel/kvm.c|2 +-
arch/x86/kernel/paravirt
This patch adds the necessary KVM specific code to allow XEN to support
the sleeping and CPU kicking operations needed by the queue spinlock PV
code.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/xen/spinlock.c | 95 --
kernel
, on the other hand, only has a minor drop in
performance for 3 or more contending tasks.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/paravirt.h | 12 ++-
arch/x86/include/asm/paravirt_types.h | 12 ++
arch/x86/include/asm/pvqspinlock.h| 232
.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 87 +
kernel/Kconfig.locks |2 +-
2 files changed, 88 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f318e78..aaf704e
On 03/12/2014 02:54 PM, Waiman Long wrote:
+
+ /*
+* Now wait until the lock bit is cleared
+*/
+ while (smp_load_acquire(qlock-qlcode) _QSPINLOCK_LOCKED)
+ arch_mutex_cpu_relax
On 03/02/2014 08:12 AM, Oleg Nesterov wrote:
On 02/26, Waiman Long wrote:
+void queue_spin_lock_slowpath(struct qspinlock *lock, int qsval)
+{
+ unsigned int cpu_nr, qn_idx;
+ struct qnode *node, *next;
+ u32 prev_qcode, my_qcode;
+
+ /*
+* Get the queue node
On 03/02/2014 08:16 AM, Oleg Nesterov wrote:
On 02/26, Waiman Long wrote:
@@ -144,7 +317,7 @@ static __always_inline int queue_spin_setlock(struct
qspinlock *lock)
int qlcode = atomic_read(lock-qlcode);
if (!(qlcode _QSPINLOCK_LOCKED) (atomic_cmpxchg(lock-qlcode
On 03/02/2014 08:31 AM, Oleg Nesterov wrote:
Forgot to ask...
On 02/26, Waiman Long wrote:
+notify_next:
+ /*
+* Wait, if needed, until the next one in queue set up the next field
+*/
+ while (!(next = ACCESS_ONCE(node-next)))
+ arch_mutex_cpu_relax
On 03/02/2014 09:10 AM, Oleg Nesterov wrote:
On 02/26, Waiman Long wrote:
+#define _ARCH_SUPPORTS_ATOMIC_8_16_BITS_OPS
+
+/*
+ * x86-64 specific queue spinlock union structure
+ */
+union arch_qspinlock {
+ struct qspinlock slock;
+ u8 lock; /* Lock bit
On 03/03/2014 05:55 AM, Paolo Bonzini wrote:
Il 28/02/2014 18:06, Waiman Long ha scritto:
On 02/26/2014 12:07 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Feb 26, 2014 at 10:14:24AM -0500, Waiman Long wrote:
Locking is always an issue in a virtualized environment as the virtual
CPU
On 03/03/2014 12:43 PM, Peter Zijlstra wrote:
Hi,
Here are some numbers for my version -- also attached is the test code.
I found that booting big machines is tediously slow so I lifted the
whole lot to userspace.
I measure the cycles spend in arch_spin_lock() + arch_spin_unlock().
The
Peter,
I was trying to implement the generic queue code exchange code using
cmpxchg as suggested by you. However, when I gathered the performance
data, the code performed worse than I expected at a higher contention
level. Below were the execution time of the benchmark tool that I sent
you:
On 02/28/2014 04:29 AM, Peter Zijlstra wrote:
On Thu, Feb 27, 2014 at 03:42:19PM -0500, Waiman Long wrote:
+ old = xchg(qlock-lock_wait, _QSPINLOCK_WAITING|_QSPINLOCK_LOCKED);
+
+ if (old == 0) {
+ /*
+* Got the lock, can clear the waiting bit now
On 02/26/2014 12:00 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Feb 26, 2014 at 10:14:20AM -0500, Waiman Long wrote:
It should be fairly easy. You just need to implement the kick right?
An IPI should be all that is needed - look in xen_unlock_kick. The
rest of the spinlock code is all generic
On 02/26/2014 12:07 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Feb 26, 2014 at 10:14:24AM -0500, Waiman Long wrote:
Locking is always an issue in a virtualized environment as the virtual
CPU that is waiting on a lock may get scheduled out and hence block
any progress in lock acquisition even when
On 02/26/2014 12:08 PM, Konrad Rzeszutek Wilk wrote:
On Wed, Feb 26, 2014 at 10:14:25AM -0500, Waiman Long wrote:
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman
On 02/27/2014 03:37 AM, Peter Zijlstra wrote:
Is this the same 8 patches you send yesterday?
Sorry for the duplication. It was the same patch. It has some minor
update in the cover-letter to include some KVM guest test results. I was
having problem locating the patch from the LKML list and
On 02/27/2014 04:31 AM, Paolo Bonzini wrote:
static __init int kvm_spinlock_init_jump(void)
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index f185584..a70fdeb 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK
config
On 02/27/2014 04:41 AM, Paolo Bonzini wrote:
Il 26/02/2014 16:14, Waiman Long ha scritto:
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
On 02/27/2014 05:40 AM, Raghavendra K T wrote:
On 02/26/2014 08:44 PM, Waiman Long wrote:
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
On 02/27/2014 07:28 AM, David Vrabel wrote:
On 26/02/14 15:14, Waiman Long wrote:
Locking is always an issue in a virtualized environment as the virtual
CPU that is waiting on a lock may get scheduled out and hence block
any progress in lock acquisition even when the lock has been freed.
One
On 02/27/2014 09:45 AM, Paolo Bonzini wrote:
Il 27/02/2014 15:18, David Vrabel ha scritto:
On 27/02/14 13:11, Paolo Bonzini wrote:
Il 27/02/2014 13:11, David Vrabel ha scritto:
This patch adds para-virtualization support to the queue spinlock
code
by enabling the queue head to kick the lock
On 02/26/2014 11:22 AM, Peter Zijlstra wrote:
On Wed, Feb 26, 2014 at 10:14:21AM -0500, Waiman Long wrote:
+struct qnode {
+ u32 wait; /* Waiting flag */
+ struct qnode*next; /* Next queue node addr */
+};
+
+struct qnode_set
On 02/26/2014 11:24 AM, Peter Zijlstra wrote:
On Wed, Feb 26, 2014 at 10:14:21AM -0500, Waiman Long wrote:
+static void put_qnode(void)
+{
+ struct qnode_set *qset = this_cpu_ptr(qnset);
+
+ qset-node_idx--;
+}
That very much wants to be: this_cpu_dec().
Yes, I will change
will add more comments to
describe the 4 possible cases and how to handle them.
On Wed, Feb 26, 2014 at 10:14:23AM -0500, Waiman Long wrote:
+static inline int queue_spin_trylock_quick(struct qspinlock *lock, int qsval)
+{
+ union arch_qspinlock *qlock = (union arch_qspinlock *)lock
On 02/27/2014 10:22 AM, Raghavendra K T wrote:
On 02/27/2014 08:15 PM, Paolo Bonzini wrote:
[...]
But neither of the VCPUs being kicked here are halted -- they're either
running or runnable (descheduled by the hypervisor).
/me actually looks at Waiman's code...
Right, this is really
optimization which will make the queue spinlock code perform
better than the generic implementation.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
arch/x86/Kconfig |1 +
arch/x86/include/asm/qspinlock.h | 41
, the disk workload improved from 416281 JPM
to 899101 JPM (+116%) with the patch. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 ++
include/asm
efficient use of the lock or finer granularity ones. The
main purpose is to make the lock contention problems more tolerable
until someone can spend the time and effort to fix them.
Waiman Long (8):
qspinlock: Introducing a 4-byte queue spinlock implementation
qspinlock, x86: Enable x86-64
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 17 +
1 files changed, 17 insertions(+), 0
-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/qspinlock.h | 20 -
include/asm-generic/qspinlock_types.h |8 ++-
kernel/locking/qspinlock.c| 192 -
3 files changed, 215 insertions(+), 5 deletions(-)
diff --git a/arch/x86
guest.
Enabling this configuration feature decreases the performance of an
uncontended lock-unlock operation by about 1-2%.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/Kconfig | 11 +
arch/x86/include/asm/qspinlock.h | 74
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/spinlock.h |4 ++--
arch/x86/kernel/kvm.c|2 +-
arch/x86/kernel/paravirt
-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 54 +
kernel/Kconfig.locks |2 +-
2 files changed, 55 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f318e78..3ddc436 100644
--- a/arch
to make sure that their CPUs will
stay scheduled in.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/paravirt.h |9 ++-
arch/x86/include/asm/paravirt_types.h | 12 +++
arch/x86/include/asm/pvqspinlock.h| 176 +
arch/x86
, the disk workload improved from 416281 JPM
to 899101 JPM (+116%) with the patch. In this case, the contended
spinlock is the mb_cache_spinlock.
Signed-off-by: Waiman Long waiman.l...@hp.com
Acked-by: Rik van Riel r...@redhat.com
---
include/asm-generic/qspinlock.h | 122 ++
include/asm
for improvement
compared with the current PV ticketlock implementation.
Waiman Long (8):
qspinlock: Introducing a 4-byte queue spinlock implementation
qspinlock, x86: Enable x86-64 to use queue spinlock
qspinlock, x86: Add x86 specific optimization for 2 contending tasks
pvqspinlock, x86
This patch adds a KVM init function to activate the unfair queue
spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
option is selected.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 17 +
1 files changed, 17 insertions(+), 0
-by: Waiman Long waiman.l...@hp.com
---
arch/x86/include/asm/qspinlock.h | 20 -
include/asm-generic/qspinlock_types.h |8 ++-
kernel/locking/qspinlock.c| 192 -
3 files changed, 215 insertions(+), 5 deletions(-)
diff --git a/arch/x86
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