Messages in this thread | | | Subject | Re: [PATCH RFC] pm_qos_requirement might sleep | From | Peter Zijlstra <> | Date | Thu, 14 Aug 2008 19:48:57 +0200 |
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On Thu, 2008-08-14 at 08:52 -0700, mark gross wrote:
> Keeping a lock around the different "target_value"s may not be so > important. Its just a 32bit scaler value, and perhaps we can make it an > atomic type? That way we loose the raw_spinlock.
My suggestion was to keep the locking for the write side - so as to avoid stuff stomping on one another, but drop the read side as:
spin_lock foo = var; spin_unlock return foo;
is kinda useless, it doesn't actually serialize against the usage of foo, that is, once it gets used, var might already have acquired a new value.
The only thing it would protect is reading var, but since that is a machine sized read, its atomic anyway (assuming its naturally aligned).
So no need for atomic_t (its read-side is just a read too), just drop the whole lock usage from pq_qos_requirement().
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