From: Juho S. <js...@ik...> - 2005-08-04 23:11:23
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<th...@ne...> wrote: > Brian Downing wrote: >> On Thu, Aug 04, 2005 at 08:43:36PM +0200, Thiemo Seufer wrote: >> > > Is there a way to reserve VM address space without implying that it will >> > > necessarily all be filled for purposes of kernel memory estimation? >> > >> > Allow memory overcommit. >> >> Right... > > Well, reserving some memory space _means_ to either have it backed by > memory/swap or to allow memory overcommit. If an admin insists in a > no-overcommit policy then his system has to provide the means for it. Sure, but there are actually three overcommit settings: 0: "The kernel attempts to estimate the amount of free memory left when userspace requests more memory." (default) 1: Infinite overcommit 2: No overcommit AFAIK, reserving memory with a @nobits section in a PT_LOAD segment counts as memory use for the heuristic that's used for case 0, while reserving it with mmap doesn't. I feel this is a bug (from our point of view there's no difference between the two cases), but I'm willing to accept that it's really working as intended. After all: <jsnell> minion: advice about heuristic <minion> #11953: Of course, this is a heuristic, which is a fancy way of saying that it doesn't work. -- Juho Snellman |