On 10/30/24 07:25, lizhe wrote:
Hi， Shuah Khan *This sounds like this change isn't required? * **not, hcd in usb_hcd_unlink_urb_from_ep() is a redundant operation, although the cost of a single instance is minimal, the cumulative cost can be significant, such as when copying a large file to a USB drive.
I am not convinced this change helps. I would rather keep the hcd argument to keep the api balanced and be able to debug a problem that requires the hcd to urb association. What are the performance numbers you are seeing with and without your patch when copying a large file to a USB drive?
*Right. Can you quantify the overhead?* Quantifying it is merely to illustrate the benefits it brings because removing it has no drawbacks, the benefits of removing HCD are obvious,
There are drawbacks as pointed out in the above paragraph. The benefits of removing HCD are not obvious to me. Maybe you can provide them by answering the performance numbers with and without your patch when copying a large file to a USB drive keeping all other variables the same. thanks, -- Shuah
