| Date | Mon, 30 Sep 2013 12:44:08 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] rwsem: reduce spinlock contention in wakeup code path |
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On Sat, Sep 28, 2013 at 12:33:36PM -0700, Linus Torvalds wrote: > The old rwlock's really have been a disappointment - they are slower > than spinlocks, and seldom/never end up scaling any better. Their > main advantage was literally the irq behavior - allowing readers to > happen without the expense of worrying about irq's.
So in part that is fundamental to the whole rw-spinlock concept.
Typically lock hold times should be short for spinlock type locks and if your hold times are short, the lock acquisition times are significant.
And a read acquisition is still a RMW operation on the lock, thus read locks are still entirely bound by the cacheline transfer of the lock itself.
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