On 10/04/2017 06:46 PM, Davidlohr Bueso wrote: > On Wed, 04 Oct 2017, Waiman Long wrote: > >> To enable the use of dlock-list in an interrupt handler, the following >> new APIs are provided for a irqsafe dlock-list: >> >> - void dlock_list_unlock_irqsafe(struct dlock_list_iter *) >> - void dlock_list_relock_irqsafe(struct dlock_list_iter *) >> - void dlock_list_add_irqsafe(struct dlock_list_node *, >> struct dlock_list_head *); >> - void dlock_lists_add_irqsafe(struct dlock_list_node *, >> struct dlock_list_heads *) >> - void dlock_lists_del_irqsafe(struct dlock_list_node *) >> >> New macros for irqsafe dlock-list: >> >> - dlist_for_each_entry_irqsafe(pos, iter, member) >> - dlist_for_each_entry_safe_irqsafe(pos, n, iter, member) > > Instead of adding more calls to the api, could we not just use the > irqsave/restore as part of the regular api? > > Thanks, > Davidlohr The irqsave/restore spinlock calls are more expensive in term of performance. I think the spin_lock_irqrestore() is especially bad in a VM as it probably causes a VMexit. So I try to avoid them unless it is absolutely necessary. Another alternative is to specify the dlock-list type at allocation time and use either regular spinlock calls or irqsave/restore calls accordingly. That will add a bit of overhead for users that don't need irq safety, but much less than using irqsave/restore for all. I was using that approach originally, but opt for the current solution for performance reason. I can revert back to my original approach and send out an updated patch. Cheers, Longman
