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SubjectRe: [PATCH 06/18] x86/ticketlock: make __ticket_spin_trylock common
On Wed, Aug 24, 2011 at 1:00 PM, Andi Kleen <> wrote:
> Can't we just get rid of the small ticket size code path?
> I couldn't benchmark any difference between the two last time
> I tried.

The small locks aren't any faster. They are just smaller.

Many data structures have spinlocks inside of them, and the smaller
spinlock *should* be able to result in smaller data structures.

Of course, that assumes that they have been packed correctly. And they
seldom are ;(

Looking at 'struct task_struct', for example, the spinlocks there
aren't next to each other, and have pointers and 'unsigned int's
around them, so rather than shrinking the data structure, it just
results in holes.


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