On Mon, Apr 12, 2010 at 08:49:40AM +0200, Ingo Molnar wrote: > AFAIK that's what Andrea has done as a test - but yes, i agree that > fragmentation is the main design worry. Well, I didn't only run a kernel compile for a couple of minutes to show how memory compaction + in-kernel set_recommended_min_free_kbytes behaved on my system. I can't claim my numbers are conclusive as it only run for 1 day and half but there was some real unmovable load on it. Plus uptime isn't the only variable, if you use the kernel to create an hypervisor product, you can leave it running VM for a much longer time than 1 day, and it won't ever generate the amount of unmovable load that I generated in one day and half I guess. I built a ton of packages including gcc, bison (which in javac triggered the anon-vma bug before I backed it out) quite some other stuff that come as a regular update with a couple of emerge world like kvirc and stuff like that. There was mutt on lkml and linux-mm maildir with some hundred thousand inodes for the email, and a dozen kernel builds and git checkouts to verify my aa.git tree. That's what I can recall. After 1 day and half I still had ~80% of the not allocated ram in order 9 and maybe ~75% (by memory, could have been more or less I don't remember exactly but I posted the exact buddyinfo so you can calculate yourself if curious) in order 10 == MAX_ORDER. The vast majority of the free ram was in order 10 after echo 3 >drop_caches and echo >compact_memory, which simulates the maximum ability of the VM to generate hugepages dynamically (of course it won't ever create such a totally compacted buddyinfo at runtime as we don't want to shrink or compact stuff unless it's really needed). Likely if I killed mutt and other running apps and I would have run drop_caches and memory compaction again I would have gotten an even higher ratio as result of more memory being freeable. One day and half isn't enough, but it was initial data, and then I had to reboot into a new #20 release to test a memleak fix I did in do_huge_pmd_wp_page_fallback... I'll try to run it for a longer time now. I guess I'll be rebuilding quite some glibc on my system as we optimize it for the kernel. -- 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>