Re: [RFC v1 0/5] fs/locks: Use plain percpu spinlocks instead of lglock to protect file_lock

[Daniel Wagner]

On 02/20/2015 05:05 PM, Andi Kleen wrote:
> Daniel Wagner <daniel.wagner@xxxxxxxxxxxx> writes:
>>
>> I am looking at how to get rid of lglock. Reason being -rt is not too
>> happy with that lock, especially that it uses arch_spinlock_t and
> 
> AFAIK it could just use normal spinlock. Have you tried that?

I have tried it. At least fs/locks.c didn't blow up. The benchmark
results (lockperf) indicated that using normal spinlocks is even
slightly faster. Simply converting felt like cheating. It might be
necessary for the other user (kernel/stop_machine.c). Currently it looks
like there is some additional benefit getting lglock away in fs/locks.c.

cheers,
daniel
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