"Ken Chen" <[EMAIL PROTECTED]> writes: > It is really sad that we always call kmap and friends for every pipe > buffer page on 64-bit arch that doesn't use HIGHMEM, or on > configuration that doesn't turn on HIGHMEM. > > The effect of calling kmap* is visible in the execution profile when > pipe code is being stressed. It is especially true on amd's x86-64 > platform where kmap() has to traverse through numa node index > calculation in order to convert struct page * to kernel virtual > address.
What is the problem? You have cache misses on the the hash table or are the instructions really an issue on a modern CPU? e.g. i out of lined virt_to_page to save space, but it could be probably inlined again if it was severly time critical. > + > +#ifdef CONFIG_HIGHMEM > +#define pipe_kmap kmap > +#define pipe_kmap_atomic kmap_atomic I think it would be better to have a somewhat generic kmap_caching() or similar interface that could be used by more subsystems. -Andi - 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/
