Re: kernel killing processes when out of swap

From: David Schultz (das_at_FreeBSD.ORG)
Date: 04/12/05

  • Next message: Divacky Roman: "Re: What is the best way to introduce delay in kernel ?" 
    Date: Tue, 12 Apr 2005 10:08:46 -0400
To: ALeine <aleine@austrosearch.net>, killing@multiplay.co.uk, freebsd-hackers@FreeBSD.ORG

    On Tue, Apr 12, 2005, Bruce M Simpson wrote:
    > On Tue, Apr 12, 2005 at 05:24:15AM -0700, ALeine wrote:
    > > machine. Having a flag to tag processes as vital to prevent them from getting
    > > killed (or to give them lower next-to-be-killed priority so that all non-vital
    > > processes get killed first) when you run out of swap would be a useful feature,
    >
    > P_SYSTEM provides something like this feature, amongst others. It is used by
    > init(8). However P_SYSTEM also says that process statistics should not be
    > maintained, and that the signals that may be dispatched to such processes
    > are restricted.

    A madvise(NULL, 0, MADV_PROTECT) is the best way to tell the
    kernel not to kill your process. You must be running as root
    to use it.

    Now that disk space is cheap, it would be even nicer if we had a
    non-overcommit mode for swap, as most System V-derived systems do.
    Then at least processes would get ENOMEM instead of SIGKILL in a
    space shortage. I don't think this would be too hard to add,
    except possibly for handling OBJT_DEFAULT objects.
    _______________________________________________
    freebsd-hackers@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
    To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"

  • Next message: Divacky Roman: "Re: What is the best way to introduce delay in kernel ?"

    Relevant Pages

    • Re: running Linux with no swap space (but lots of RAM)
      ... |>| It's a statement of fact: You are advocating to save disk space at the ... |>| expense of RAM. ... what would have to be running to make use of 256 GB of swap? ... |>A page that is dirty and would get swapped out can instead take up RAM ...
      (comp.os.linux.development.system)
    • Re: running Linux with no swap space (but lots of RAM)
      ... |>> to dirty, but inactive pages associated with some applications. ... | It's a statement of fact: You are advocating to save disk space at the ... | expense of RAM. ... what would have to be running to make use of 256 GB of swap? ...
      (comp.os.linux.development.system)
    • Re: growfs for solaris 8
      ... Yes you can steal a bit of swap but you are going to need to steal a really big piece of swap to meet future requirements. ... Remember that there is no pain quite like backing up your entire system, repartitioning the disk to make room where none is left and then restoring your system. ... Being generous may waste a bit of disk space but being too stingy will cost you many hours and if you are any good at all, your time is worth more than a little disk space. ... I suspect that an hour of your time costs your employer at least that much. ...
      (comp.unix.solaris)
    • Re: Partitioning scheme for file/mail server
      ... make swap 2x the maximum amount of memory that can be fitted ... If you're using Linux software RAID ... (This system uses LVM, but not RAID, and you don't need LVM for this, ... depends on how much disk space you have in total; ...
      (uk.comp.os.linux)
    • Re: kernel killing processes when out of swap
      ... Having a flag to tag processes as vital to prevent them from getting ... > processes get killed first) when you run out of swap would be a useful feature, ...
      (freebsd-hackers)