On Tue, 18 Sep 2007, Luis R. Rodriguez wrote: > > An extra branch is created on MMIO-only devices on read/writes on the > IO_COND macro using this interface -- or is this optimized out? Umm. Does anybody actually have any performance numbers? The thing is, those things are *cheap* compared to the IO. And any high-performance device will be using DMA for the real IO, so we're not generally even talking about any performance-critical stuff. Quite frankly, if performance is a _real_ reason to avoid ioread*/iowrite*, I'll happily accept read*/write*, but it would be needed to be backed up by real numbers. Can you even measure it? I would definitely *not* encourage the notion that people should use readl/writel because of "performance reasons". That may be valid for some fbcon driver, but those drivers go to other extremes (ie they use "__raw_writel()" etc, and MTRR's etc). If you don't use write-combining memory regions, the performance argument is not really valid. Linus - 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
