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- Newsgroups: comp.unix.aix
- Path: sparky!uunet!utcsri!torn!utzoo!utdoe!torag!jrh!jrh
- From: jrh@jrh.uucp (James R. Hamilton)
- Subject: Re: Virtual Memory curiosity
- Message-ID: <1992Nov12.131230.130467@jrh.uucp>
- Keywords: VM overflow response
- Organization: private system, Toronto, Ontario
- References: <bmarlowe.721422470@ka>
- Distribution: usa
- Date: Thu, 12 Nov 1992 13:12:30 GMT
- Lines: 30
-
- In article <bmarlowe.721422470@ka> bmarlowe@ka.reg.uci.edu (Brett Marlowe) writes:
- >
- >I've heard rumor that AIX will pick processes to kill off to avoid
- >running out of virtual memory? Can anyone verify this and if this is
- >true a) is there a way to disable this "feature" and b) what idiot
- >decided that randomly killing processes was a good idea??!!
- >
- It is true that AIX will start killing process when it runs out of
- page space. You can disable this feature (i.e. protect a process)
- by it calling "signal(SIGDANGER, SIG_IGN)". WRT to the idiot that
- decided to randomly kill processes, the decision is not random --
- processes are killed youngest first (in AIX 3.2) and if they ignore
- SIGDANGER then they are not killed at all.
-
- To be sure there is lots of room for debate here. Some will argue that
- the SUN decision of forcing there to be backing store for all virtual
- memory granted is the correct decision since memory shortages are
- caught at malloc time. Others prefer the AIX decision of only allocating
- backing store as required. The advantage of this is large sparse arrays
- can be allocated on AIX but not on SUN. The disadvantage is that backing
- store shortages are not caught at malloc time. I can work with either
- decision.
-
- --jrh
-
- --
-
- James R. Hamilton inet: jrh@jrh.gts.org
- telephone: +1 416 493 4162 uunet: ...!uunet!jrh!jrh
- Toronto, Canada work: jrh@torolab6.vnet.ibm.com
-