Re: [RFC] USB: core/xhci: add a buffer in urb for host controller private data

["David Wang" <00107082@163.com>]

At 2025-05-12 23:34:41, "Alan Stern" <stern@rowland.harvard.edu> wrote:
>On Mon, May 12, 2025 at 11:07:24PM +0800, David Wang wrote:
>> ---
>> I was checking memory allocation behaviors (via memory profiling[1]),
>> when I notice a high frequent memory allocation in xhci_urb_enqueue, about
>> 250/s when using a USB webcam. If those alloced buffer could be kept and
>> reused, lots of memory allocations could be avoid over time.
>> 
>> This patch is just a POC, about 0/s memory allocation in xhci with this
>> patch, when I use my USB devices, webcam/keyboard/mouse. 
>> 
>> A dynamic cached memory would be better: URB keep host controller's
>> private data, if larger size buffer needed for private data, old buffer
>> released and a larger buffer alloced.
>
>This sounds like a better approach; you should try it.  Allocations and 
>dellocations from a private memory pool can be really quick.  And it 
>wouldn't waste space on buffers for URBs that don't need them (for 
>example, URBs used with other host controller drivers).
>
>Alan Stern

Thanks for the quick feedback~
I will work on it and update later~

David