W dniu 18 kwietnia 2011 16:06 uÅytkownik Ivo Van Doorn <ivdoorn@xxxxxxxxx> napisaÅ: > Hi, > >>> All register reads/writes in rt2800usb were previously done with >>> rt2800_register_read/rt2800_register_write. These however indirectly >>> call rt2x00usb_register_read/rt2x00usb_register_write which adds an >>> additional overhead of at least one call and several move instructions >>> to each register access. >>> >>> Replacing the calls to rt2800_register_read/rt2800_register_write with >>> direct calls to rt2x00usb_register_read/rt2x00usb_register_write gets >>> rid of quite a number of instructions in the drivers hotpaths (IRQ >>> handling and txdone handling). >>> >>> For consistency replace all references to rt2800_register_read/write >>> with the rt2x00usb_register_read/write variants. >> >> This way you loose abstraction of writes/reads for usb vs. pci. And >> you still can not optimize rt2800lib code which is shared between usb >> and pci. > > Well the rt2800lib code is not changed by this (or patch 20 of this series). > >> Wouldn't this be better to create two pointers in struct rt2x00_dev. >> One for writing function and one for reading function? Am I right >> thinking calling functions by pointers is quite fast? Or is this still >> noticeably slower than using proper functions directly? > > We already have the pointer inside struct rt2x00_dev which references > the register access functions for rt2800pci/usb. These pointers are used > by rt2800lib to access the common registers. What this patch does, is > optimize the case where we exactly know which function we need, because > we are in the actual driver. Ah, OK, I can see rt2800_register_read/write indeed are using pointers: rt2800ops->register_read(rt2x00dev, offset, value); So I believe it was still not fast enough for you. It's OK then. I just though you were using if (dev->usb) rt2x00usb_register_read else ... > As for the performance, I'll let Helmut comment on that as he created patch 20, > which introduced this change to rt2800pci. :) -- RafaÅ -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
