Messages in this thread | | | Date | Thu, 16 Sep 2004 19:45:30 +0200 | From | Arjan van de Ven <> | Subject | Re: [PATCH] flexmmap: optimise mmap_base gap for hard limited stack |
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On Thu, Sep 16, 2004 at 06:56:13PM +0200, Utz Lehmann wrote: > Hi > > With the flexmmap memory layout there is at least a 128 MB gap between > mmap_base and TASK_SIZE. I think this is for the case that a running process > can expand it's stack soft rlimit. > > If there is a hard limit for the stack this minium gap is just a waste of > space. This patch reduce the gap to the hard limit + 1 MB hole. If a process > has a 8192 KB hard limit it have additional 119 MB space available over the > current behavior.
I'm not so convinced this is the right approach... a bit of room for the apps to increase their stack sounds useful. (and a "reasonable" amount is SuS specified afaik, 128Mb is quite reasonable)
> And the current implemention has a problem. If the stack soft limit is > 128+ MB there is no hole between the stack and mmap_base. If there is a > mapping at mmap_base stack overflows are not detected. The patch made a > 1MB hole between them.
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