> Demand-paging the hugepages is a decent feature to have, and ISTR resisting > it before for this reason. > > Even though it's early in the 2.6 series I'd be a bit worried about > breaking existing hugetlb users in this way. Yes, the pages are > preallocated so it is unlikely that a working setup is suddenly going to > break. Unless someone is using the return value from mmap to find out how > many pages they can get. Hmm what a coincidence, I was chasing a problem where large page allocations would fail even though I clearly had enough large page memory free. It turns out we were tripping the overcommit logic in do_mmap. I had 30GB of large page and 2GB of small pages and of course cap_vm_enough_memory was looking at the small page pool. Setting overcommit to 1 fixed it. It seems we can solve both problems by having a separate hugetlb overcommit policy. Make it strict and you wont have OOM problems on large pages and I wont hit my 30GB / 2GB problem. Anton - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.htmlReceived on Sat Mar 13 23:07:56 2004
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