Re: [PATCH 4/4] cpuset,mm: use rwlock to protect task->mempolicy and mems_allowed

Peter Zijlstra
2010-03-04T14:58:29Z

On Thu, 2010-03-04 at 14:30 +1100, Nick Piggin wrote:
>
> Thanks for working on this. However, rwlocks are pretty nasty to use
> when you have short critical sections and hot read-side (they're twice
> as heavy as even spinlocks in that case).

Should we add a checkpatch.pl warning for them?

There really rarely is a good case for using rwlock_t, for as you say
they're a pain and often more expensive than a spinlock_t, and if
possible RCU has the best performance.