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...mization. Also note that I don't have this cmpxchg loop anymore. > kernel/locking/qspinlock.c | 32 ++++++++++++++++++++++++++++++-- > 1 files changed, 30 insertions(+), 2 deletions(-) > > diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c > index 55601b4..497da24 100644 > --- a/kernel/locking/qspinlock.c > +++ b/kernel/locking/qspinlock.c > @@ -216,6 +216,7 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval) > static inline int trylock_pending(struct qspinlock *lock, u32 *pval) > { > u32 old, new, val = *pval; > + int retry =...

...mization. Also note that I don't have this cmpxchg loop anymore. > kernel/locking/qspinlock.c | 32 ++++++++++++++++++++++++++++++-- > 1 files changed, 30 insertions(+), 2 deletions(-) > > diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c > index 55601b4..497da24 100644 > --- a/kernel/locking/qspinlock.c > +++ b/kernel/locking/qspinlock.c > @@ -216,6 +216,7 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval) > static inline int trylock_pending(struct qspinlock *lock, u32 *pval) > { > u32 old, new, val = *pval; > + int retry =...

...lock is still quite a bit faster. Signed-off-by: Waiman Long <Waiman.Long at hp.com> --- kernel/locking/qspinlock.c | 32 ++++++++++++++++++++++++++++++-- 1 files changed, 30 insertions(+), 2 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 55601b4..497da24 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -216,6 +216,7 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval) static inline int trylock_pending(struct qspinlock *lock, u32 *pval) { u32 old, new, val = *pval; + int retry = 1; /* * trylock || pending @...

...a bit of slowdown in the pending bit code path. >> kernel/locking/qspinlock.c | 32 ++++++++++++++++++++++++++++++-- >> 1 files changed, 30 insertions(+), 2 deletions(-) >> >> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c >> index 55601b4..497da24 100644 >> --- a/kernel/locking/qspinlock.c >> +++ b/kernel/locking/qspinlock.c >> @@ -216,6 +216,7 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval) >> static inline int trylock_pending(struct qspinlock *lock, u32 *pval) >> { >> u32 old, new, val =...

...10.00 198.20 4.80 Signed-off-by: Waiman Long <Waiman.Long at hp.com> --- kernel/locking/qspinlock.c | 61 +++++++++++++++++++++++++++++++------------ 1 files changed, 44 insertions(+), 17 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 497da24..80fe9ee 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -98,23 +98,29 @@ static inline struct mcs_spinlock *decode_tail(u32 tail) * can allow better optimization of the lock acquisition for the pending * bit holder. */ -#if _Q_PENDING_BITS == 8 - struct __qspinlo...

v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex patches into smaller ones to ease review effort. - Fix a racing condition in the PV qspinlock code. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving

v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex patches into smaller ones to ease review effort. - Fix a racing condition in the PV qspinlock code. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving