Re: [PATCH 1/1] mlock: split the shmlock_user_lock spinlock into per user_struct spinlock

rajman mekaco
2012-05-12T03:10:42Z

>>
>> Maybe you didn't read my last email:
>> If 2 different user-mode processes executing on 2 CPUs under 2 different
>> users want to access the same shared memory through the
>> shmctl(SHM_LOCK) / shmget(SHM_HUGETLB) / usr_shm_lock
>> primitives, they could compete/spin even though their user_structs
>> are different.
>>
>> Can you please correct me if I am missing some crucial point of
>> understanding ?
>
>
> Mlock is a very very expensive operation.
>
> Updating the mlock statistics is a very cheap operation.
>
> Does this spinlock ever show up contention wise?

I just tested for working and not contention. :)
I was just going by correctness of concept.
But I understand what you say and I will try to actually test contention
for this in the coming days.

>
> --
> All rights reversed