* Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > On Mon, Apr 12, 2010 at 04:22:30AM -0700, Arjan van de Ven wrote: > > > > Now hugepages have some interesting other advantages, namely they save > > pagetable memory..which for something like TPC-C on a fork based database > > can be a measureable win. > > It doesn't save pagetable memory (as in `grep MemFree /proc/meminfo`). [...] It does save in terms of CPU cache footprint. (which the argument was about) The RAM is wasted, but are always cache cold. > [...] I think the saving in pagetables isn't really interesting... [...] i think it's very much interesting for 'pure' hugetlb mappings, as a next-step thing. It amounts to 8 bytes wasted per 4K page [0.2% of RAM wasted] - much more with the kind of aliasing that DBs frequently do - for hugetlb workloads it is basically roughly equivalent to a +8 bytes increase in struct page size - few MM hackers would accept that. So it will have to be fixed down the line. Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>