On Fri, Jul 15, 2011 at 02:10:21AM +0200, Lennert Buytenhek wrote: > On Thu, Jul 07, 2011 at 01:38:25PM +0100, Russell King - ARM Linux wrote: > > > > > > > I suppose for the majority of the cases, the overhead of the indirect > > > > > > function call is near-zero, compared to the overhead of the cache > > > > > > management operation, so it would only make a difference for coherent > > > > > > systems without an IOMMU. Do we care about micro-optimizing those? > > > > > > FWIW, when I was hacking on ARM access point routing performance some > > > time ago, turning the L1/L2 cache maintenance operations into inline > > > functions (inlined into the ethernet driver) gave me a significant and > > > measurable performance boost. > > > > On what architecture? Can you show what you did to gain that? > > Patch is attached below. It's an ugly product-specific hack, not > suitable for upstreaming in this form, etc etc, but IIRC it gave me > a ~5% improvement on packet routing. Do you know how much is contributed from each change - L1, L2, moving dma_cache_maint() inline, removing the virt_addr_valid() etc? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
