Re: [PATCH] locking/percpu_rwsem: Rewrite to not use rwsem

Peter Zijlstra
2019-08-06T17:15:25Z

On Tue, Aug 06, 2019 at 06:17:42PM +0200, Oleg Nesterov wrote:

> but this will also wake all the pending readers up. Every reader will burn
> CPU for no reason and likely delay the writer.
>
> In fact I'm afraid this can lead to live-lock, because every reader in turn
> will call __percpu_up_read().

I didn't really consider that case important; because of how heavy the
write side is, it should be relatively rare.

> How about 2 wait queues?

That said, I can certainly try that.