On Thu, Jun 07, 2012 at 10:54:10AM +1000, NeilBrown wrote: > On Mon, 04 Jun 2012 16:01:53 +0800 Shaohua Li <shli@xxxxxxxxxx> wrote: > > > Add a per-stripe lock to protect stripe specific data, like dev->read, > > written, ... The purpose is to reduce lock contention of conf->device_lock. > > I'm not convinced that you need to add a lock. > I am convinced that if you do add one you need to explain exactly what it is > protecting. > > The STRIPE_ACTIVE bit serves as a lock and ensures that only one process can > be in handle_stripe at a time. > So I don't think dev->read actually needs any protection (though I haven't > checked thoroughly). > > I think the only things that device_lock protects are things shared by > multiple stripes, so adding a per-stripe spinlock isn't going to help remove > device_lock. This sounds not true to me. both the async callbacks and request completion access stripe data, like dev->read. Such things are not protected by STRIPE_ACTIVE bit. Thought we can delete STRIPE_ACTIVE bit with stripe lock introduced. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
