Messages in this thread | | | Date | Mon, 14 Sep 2015 15:57:49 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v6 5/6] locking/pvqspinlock: Allow 1 lock stealing attempt |
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On Fri, Sep 11, 2015 at 02:37:37PM -0400, Waiman Long wrote: > +#define queued_spin_trylock(l) pv_queued_spin_trylock_unfair(l) > +static inline bool pv_queued_spin_trylock_unfair(struct qspinlock *lock) > +{ > + struct __qspinlock *l = (void *)lock; > + > + if (READ_ONCE(l->locked)) > + return 0; > + /* > + * Wait a bit here to ensure that an actively spinning vCPU has a fair > + * chance of getting the lock. > + */ > + cpu_relax(); > + > + return cmpxchg(&l->locked, 0, _Q_LOCKED_VAL) == 0; > +}
> +static inline int pvstat_trylock_unfair(struct qspinlock *lock) > +{ > + int ret = pv_queued_spin_trylock_unfair(lock); > + > + if (ret) > + pvstat_inc(pvstat_utrylock); > + return ret; > +} > +#undef queued_spin_trylock > +#define queued_spin_trylock(l) pvstat_trylock_unfair(l)
These aren't actually ever used...
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