Patch Name:  PHKL_5925

Patch Description: s700 10.00 Fixes system hang

Creation Date: 95/08/11

Post Date:  95/08/15

Hardware Platforms - OS Releases:
        s700: 10.00

Products: N/A

Filesets:
        OS-Core.CORE-KRN

Automatic Reboot?: Yes

Status: General Release

Critical:
        Yes
        PHKL_5925: HANG

Path Name:  /hp-ux_patches/s700/10.X/PHKL_5925

Symptoms:
        PHKL_5925:
        The system hangs when there is heavy load and some processes
        which are swapped out use a lot of large memory mapped
        segments.

Defect Description:
        PHKL_5925:
        The system hangs because most processes are swapped out
        due to heavy load and the process which is the lead
        candidate to be brought in needs a lot of pages much
        more than freemem. So the swapper waits until freemem
        is high enough for this process to be brought in
        but since all the other processes which are swapped
        out are not the lead candidate and there is no memory
        pressure in the system the vhand does not
        push out any more pages. This causes the whole
        system to hang until something happens to disturb
        this equilibrium point.

        This can be reproduced by allocating a lot of
        private memory mapped segments of atleast
        33 pages each. By introducing heavy load
        this process along with many other procces
        are forced to be swapped out
        This situation can lead to a hang.

SR:
        5003269464

Patch Files:
        /usr/conf/lib/libhp-ux.a(vm_sched.o)
        /usr/conf/lib/libhp-ux.a(vm_vfd.o)

what(1) Output:
        /usr/conf/lib/libhp-ux.a(vm_sched.o):
                vm_sched.c    $Date: 95/08/11 13:33:04 $ $Revision:
                        1.55.91.3 $ PATCH_10.0 (PHKL_5925)
        /usr/conf/lib/libhp-ux.a(vm_vfd.o):
                vm_vfd.c      $Date: 95/08/11 13:31:29 $ $Revision:
                        1.14.91.3 $ PATCH_10.0 (PHKL_5925)

cksum(1) Output:
        1412748026 18400 /usr/conf/lib/libhp-ux.a(vm_sched.o)
        1068024339 13740 /usr/conf/lib/libhp-ux.a(vm_vfd.o)

Patch Conflicts: None

Patch Dependencies:  None

Hardware Dependencies:  None

Other Dependencies:  None

Supersedes:  None

Equivalent Patches:
        PHKL_5767:
        s700: 10.01

Patch Package Size:  80 Kbytes

Installation Instructions:
        Please review all instructions and the Hewlett-Packard
        SupportLine User Guide or your Hewlett-Packard support terms
        and conditions for precautions, scope of license,
        restrictions, and, limitation of liability and warranties,
        before installing this patch.
        ------------------------------------------------------------
        1. Back up your system before installing a patch.

        2. Login as root.

        3. Copy the patch to the /tmp directory.

        4. Move to the /tmp directory and unshar the patch:

                cd /tmp
                sh PHKL_5925

        5. For a standalone system, run swinstall to install the
           patch:

               swinstall -x autoreboot=true -x match_target=true \
                       -s /tmp/PHKL_5925.depot

        By default swinstall will archive the original software in
        /var/adm/sw/patch/PHKL_5925.  If you do not wish to retain a
        copy of the original software, you can create an empty file
        named /var/adm/sw/patch/PATCH_NOSAVE.

        Warning: If this file exists when a patch is installed, the
                 patch cannot be deinstalled.  Please be careful
                 when using this feature.

        It is recommended that you move the PHKL_5925.text file to
        /var/adm/sw/patch for future reference.

        To put this patch on a magnetic tape and install from the
        tape drive, use the command:

                swpackage -s /tmp/PHKL_5925.depot -x   \
                        target_type=tape -d /dev/rmt/0m PHKL_5925

Special Installation Instructions:  None