Re: [PATCH 2/4, v2] x86: enlightenment for ticket spin locks - Xen implementation

From: Jan Beulich
Date: Wed Jun 30 2010 - 04:51:40 EST

>>> On 30.06.10 at 10:05, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Tue, 2010-06-29 at 15:32 +0100, Jan Beulich wrote:
>> +static DEFINE_PER_CPU(arch_rwlock_t, spinning_rm_lock) =
> why is that an arch_ lock?

Because I don't think it is appropriate to use anything higher level
in the callouts from the lock/unlock inline functions. The alternative
would be an open coded lock, which seems much less desirable to

> why is that a rwlock?, those things are useless.

Because potentially each CPU's lock gets acquired for reading during
unlock, while only the locking CPU's one needs to be acquired for
writing during lock.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at