Hi Javi, On Wed, Jan 06, 2016 at 10:07:13AM +0000, Javi Merino wrote: > On Wed, Jan 06, 2016 at 04:53:44PM +0800, Leo Yan wrote: > > k_po/k_pu are two proportional term constants and essentially they have > > fixed ratio compared with sustainable power. In current implementation, > > k_po and k_pu are absolute value after calculation and cannot represent > > the ratio relationship with sustainable power; as a result, when change > > sustainable power we cannot smoothly change proportional term constant. > > In v2 Daniel said that the use case was made up. Can you elaborate on > why we need this? When I did IPA profiling on Hikey, I tried to set different sustainable power. But after changed sustainable power, k_po and k_pu were stale value which calculated by old sustainable power. So with this patch, it's more convinence for profiling and can avoid confusion for k_po/k_pu after update sustainable power. > > So this patch series introduces k_po_ratio and k_pu_ratio, which > > represent the ratio value compared against sustainable power. Also add > > sys file system nodes for them for easily update them from userspace and > > update a bit in documentation. > > Actually, it makes it harder to update from userspace. Now userspace > can't set a k_po/k_pu any more, and it's forced to set them as ratios > of sustainable power. I'd rather not do this unless there is a good > reason for it. We use ratios of sustainable power to calculate k_po/k_pu, so if user explicitly specify ratio values we can easily to update k_po/k_pu after we change sustainable power. Otherwise, it's hard to get to know the real ratio values of sustainable power. Please review below case: - If we set new sustainable power, then actually in kernel it should update k_po/k_pu so that can keep fixed ration; - At the meantime, user can set k_po/k_pu from sys file node so that eventually change ratio; So here has race condition with updating k_po/k_pu and the code is hard to distinguish what is real real ratio. If have explicit parameters for ratios, then will be much clear. Thanks, Leo Yan -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
