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    SubjectRe: Some questions about linux kernel.
    On Wed, 15 Mar 2000, James Sutherland wrote:

    > > > we can SIGTERM the process first. In the case of the Oracle server, it
    > > > should be able to use this to sync the database, close connections and
    > > > exit gracefully.
    > >
    > > All that without being able to allocate more memory?
    >
    > It's just closing files and sockets, flushing buffers etc. It should be
    > able to manage that without needing to increase memory usage at all.

    I am not sure about that -- Oracle has rather complex ideas about
    transactions, data consistency and transaction logs. Other
    "mission-critical" applications may be even more finicky about the state
    of the system when their shutdown procedures are running.

    > > > Later, I would like to add priorities (e.g. try to kill x, y and z first,
    > > > then kill all the non-root processes (or the non-dbuser processes, or
    > > > whatever), then kill the rest.)
    > > >
    > > > No strategy will ever be perfect, but this system is pretty good, IMO.
    > >
    > > Why not just make some means to set strategy from userspace? Say, init
    > > runs xdm through a wrapper that gives it an ability to set the
    > > survivability policy for its children, and xdm runs local X server with
    > > high "proprity to survive". When user logs in, Xsession runs with this
    > > ability lost, so mortal user won't be able to mess with this policy unless
    > > he runs some restrictive setuid wrapper for his programs (not unlike
    > > sudo), so some "important" programs can run as user yet will not be killed
    > > too soon. inetd runs with high "priority to survive" yet the policy is
    > > set so its children won't inherit it unless they are run through a
    > > wrapper. And to make things even more flexible, sysadmin or some
    > > "smart" daemon then can use something similar to renice(8) that will be
    > > able to change this policy for already running processes.
    >
    > That's what I suggested originally.

    And what is wrog with that? As I understand it, it shouldn't be hard to
    implement in kernel, and arguments about particular policies can be left
    to userspace developers.

    --
    Alex


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