Messages in this thread | | | Date | Tue, 25 Nov 2003 16:23:10 +0100 | From | "Ihar 'Philips' Filipau" <> | Subject | Re: 2.2/2.4/2.6 VMs: do malloc() ever return NULL? |
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Arjan van de Ven wrote: > > that is due to the overcommit policy that your admin has set. > You can set it to disabled and then malloc will return NULL in userspace >
Target (patched by mvista) system works as expected in case of memory being touch. But in case of "for(;;) malloc(N)" it still gets 1.8GB memory allocated. (this is ppc32 - looks like 2/2 memory split) So it doesn't look like working at all. So basicly pool allocation used in carrier grade systems goes south: even with overcommit_memory=-1 && malloc()!=0 you can not be sure that memory is really allocated. Not good.
Vanilla 2.4.22 (this is x86) (with HZ=1024, if it does matter).
after '# echo -1 >/proc/sys/vm/overcommit_memory' 1. test app with memory touch still gets killed by oom_killer. (so no malloc() == NULL) 2. test app w/o memory touch still can happily allocate 2.8GB of memory (x86 - looks like 3/1 memory split) and only then gets NULL pointer - oom_killer is silent.
But thanks for pointers in any way...
-- Ihar 'Philips' Filipau / with best regards from Saarbruecken. -- _ _ _ Because the kernel depends on it existing. "init" |_|*|_| literally _is_ special from a kernel standpoint, |_|_|*| because its' the "reaper of zombies" (and, may I add, |*|*|*| that would be a great name for a rock band). -- Linus Torvalds
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