Andy Whitcroft wrote: >> To my knowledge, moving to a higher base page size has its advantages in >> TLB reach, but brings with it some pretty serious downsides. Especially >> in caching small files. Internal fragmentation in the page cache >> significantly affecting system performance. So much so that development >> is ongoing to see if supporting sub-base-page objects in the buffer >> cache could be beneficial.
On Fri, Apr 27, 2007 at 01:08:17AM +1000, Nick Piggin wrote: > I think 16K would be pretty reasonable (ia64 tends to use it). I guess > powerpc went to 64k either because that's what databases want or because > their TLB refills are too slow, so the internal fragmentation bites > them a lot harder. > But that was more of a side comment, because I still think io controllers > should be easily capable of operation on 4K pages. Graphics cards are, > aren't they? Base page size need only be a power-of-two multiple of the MMU pagesize. ISTR the 64KB PAGE_SIZE in ppc64 being motivated by TLB considerations. There is not going to be a way to improve how well IO controllers deal with 4K pages. The scatter/gather lists for smaller fragments will require more device communication overhead no matter what, and furthermore, the more discontiguity, the more seekiness. -- wli - 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/
