Re: [linux-usb-devel] Re: SLAB vs. pci_alloc_xxx in usb-uhci patch [RFC: API]

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Fri Mar 09 2001 - 16:38:35 EST


> I wonder if it may be feasible to allocate a bunch of contiguous
> pages. Then, whenever the hardware returns a bus address, subtract
> the remembered bus address of the zone start, add the offset to
> the virtual and voila.

Even if not you can hash by page number not low bits so the hash is way
smaller. You (in most cases) can also write the entry number in the relevant
tables onto the end of the object in spare space (or in front of it)

Something as trivial as

        struct usb_thingy
        {
                u32 thing_id;
                u32 flags;
                struct usb_thingy *next;
#ifndef __LP64__
                u32 pad
#endif
                struct usb_controller_goo goo;
        }

Alan

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This archive was generated by hypermail 2b29 : Thu Mar 15 2001 - 21:00:11 EST