On Tue, 2024-09-10 at 09:52 -0700, Bart Van Assche wrote: > > External email : Please do not click links or open attachments until > you have verified the sender or the content. > On 9/10/24 5:34 AM, Peter Wang (王信友) wrote: > > On Mon, 2024-09-09 at 16:11 -0700, Bart Van Assche wrote: > >> Simplify __ufshcd_send_uic_cmd() by always initializing the > >> uic_cmd::done completion. This is fine since the time required to > >> initialize a completion is small compared to the time required to > >> process an UIC command. > > > > The time to compare should not be with the UIC command process > time. > > It should be compared with the time for the "if (completion)" > > conditional > > expression. We cannot justify increasing the latency of sending a > UIC > > command just because the UIC command process time is longer. > > Although I appreciate your concern about performance, I don't think > that > the above feedback is appropriate. On my test setup UIC commands take > between 20 and 1500 microseconds to complete. A single > init_completion() > call takes about 0.01 microseconds. So I don't think that the time > spent > in init_completion() matters for UIC commands. Additionally, this > patch > only introduces an init_completion() call for power management > commands > and not any other type of UIC command. > > Thanks, > > Bart. > Hi Bart, I have concerns about adding latency just for power management commands. This is because when DVFS needs performance and wants to scale up, it will take extra time to complete the scaling up process. However, I agree that such a 0.01ms delay may not have a significant impact on the overall scale-up and read/write process. It might be helpful to add this information to the patch description. Thank you. Peter Reviewed-by: Peter Wang <peter.wang@xxxxxxxxxxxx>
