Re: Out Of Memory in v. 2.1

Brandon S. Allbery KF8NH (allbery@kf8nh.apk.net)
Tue, 06 Oct 1998 17:26:02 -0300


In message <5llnmtepay.fsf@tequila.systemsz.cs.yale.edu>, Stefan Monnier
writes
:
+-----
| >>>>> "Andrea" == Andrea Arcangeli <andrea@e-mind.com> writes:
| > (overcommit is a check that _sbrk()_ does before use mmap to map the
| > memory)
|
| I don't understand. I thought overcommitment is when virtual address space i
+--->8

I think what Andrea is saying is that mmap()-based memory allocation just
grabs a pte without allocating any memory, so swap overcommit isn't relevant
at that time. (It becomes relevant when the process writes to that memory,
triggering a COW, which as you noted *does* involve swap overcommit.)

-- 
brandon s. allbery	[os/2][linux][solaris][japh]	 allbery@kf8nh.apk.net
system administrator	     [WAY too many hats]	   allbery@ece.cmu.edu
electrical and computer engineering					 KF8NH
carnegie mellon university

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