Newsgroups: comp.sys.hp

>    Something must be wrong with your configuration.  We have dozens of
>    HP 7X0 and hundreds of Sun workstations.  Our experience under a
>    variety of conditions is that the HPs are *much* faster than the
>    SparcStation IIs.  Everybody wants an HP now ;-)
>
>    Could the difference be memory?  We found an enormous speed-up in our
>    HP 7X0s when we increased all of their memory from 16-32mg to 48mg.
>    Swapping and paging on this class of machine is a real killer.
>
>    regards,
>    fletcher

The VM has been tightened up for 9.0.  A patch for 8.07 is available as
PHKL_1065.  I've appended the README for the patch.

Perry Scott
HP Ft Collins





Patch Name: PHKL_1065

Patch Description: Fix interactive hangs caused by low memory and swapping.

    Note:  This patch is essentially an 8.07 version of a subset of the
    virtual memory improvements being made to 9.0 for work stations.

    Problems this patch addresses:

        This patch improves interactive response times while the system is
        heavily paging or swapping, particularly during transient periods
        where the system would run out of physical memory.  However, It
        could either improve or degrade the total time needed to run a
        program while heavily paging.  That is, this patch's intent is to
        improve response time, not throughput, which will likely improve but
        could worsen.  For example, a set of memory intensive processes are
        less likely to spend time being temporarily completely swapped to
        disk, so more processes will be interfering with each other at a
        time, possible giving slower overall throughput than if they'd been
        run fewer at a time.

        There are, of course, performance problems in hp-ux, which may
        appear related to virtual memory, but which this patch does not
        address.

        Specific problems addressed by this patch are

        - During periods where a small number of processes quickly and
          continually absorb all free physical memory.  Usually the startup
          phase of a large process.  Typically, the system appears to hang
          until the such a period ends.

        - During the swapping of large processes.  Other disk accesses may
          temporarily be suspended, potentially causing a temporary hang.

        - "nice" had little impact when the system is paging heavily

    How this patch addresses the above problems:

        When "nice" is used to lower the priority of batch processes, this
        patch greatly improves the situations described above, and may
        somewhat improve other performance problems caused by memory stress.
        Even if "nice" is not used, improvement in interactive response will
        be seen, but using "nice" gives considerably better results.

        The patch includes a new page-out algorithm, a less intrusive
        swapping mechanism, fixes defects causing lockup situations while
        there is no free physical memory, and reduces the chance of the
        system getting in a situation where it has no free physical memory.

        It would be wise to first run this patch on a trial basis and see if
        your particular performance problems are improved.