On Wed, Nov 28, 2012 at 5:29 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > But it doesn't have to walk the children. Moreover, with counters it only Yeah, I got it, it is the advantage of counter, but with extra 'int' field introduced in 'struct device'. > needs to walk the whole path if all devices in it need to be updated. For > example, if you call pm_runtime_set_memalloc_noio(dev, true) for a device > whose parent's counter is greater than zero already, you don't need to > walk the path above the parent. We still can do it with the flag only, pm_runtime_set_memalloc_noio(dev, true) can return immediately if one parent or the 'dev' flag is true. But considered that the pm_runtime_set_memalloc_noio(dev, false) is only called in a very infrequent path(network/block device->remove()), looks the introduced cost isn't worthy of the obtained advantage. So could you accept not introducing counter? and I will update with the above improvement you suggested. Thanks, -- Ming Lei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>