On Mon, 2007-03-19 at 13:05 -0700, Adam Litke wrote: > For the common case (vma->pagetable_ops == NULL), we do almost the > same thing as the current code: load and test. The third instruction > is different in that we jump for the common case instead of jumping in > the hugetlb case. I don't think this is a big deal though. If it is, > would an unlikely() macro fix it?
I wouldn't worry about micro-optimizing it at that level. The CPU does enough stuff under the covers that I wouldn't worry about it at all. I wonder if the real differential impact (if any) is likely to come from the pagetable_ops cacheline being hot or cold, since it is in a different place in the structure than the flags. But, from a quick glance I see a few vm_ops references preceding pagetable_ops references, so the pagetable_ops cacheline might already be hot most of the time. BTW, are there any other possible users for these things other than large pages? -- Dave - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
