Patch Name: PHKL_18551 Patch Description: s700 10.20 Buffer cache fixes for hangs and performance Creation Date: 99/05/06 Post Date: 99/05/12 Hardware Platforms - OS Releases: s700: 10.20 Products: N/A Filesets: OS-Core.CORE-KRN Automatic Reboot?: Yes Status: General Superseded Critical: No (superseded patches were critical) PHKL_17714: HANG PHKL_17624: HANG Path Name: /hp-ux_patches/s700/10.X/PHKL_18551 Symptoms: PHKL_18551: ( SR: 4701422873 DTS: JAGab11378 ) Systems that continuously write and truncate a large number of files could see CPU consumption increase over time for those buffer cache routines that traverse hash link-lists. PHKL_17714: ( SR: 1653286468 DTS: JAGaa44872 ) Processes may hang when accessing files in a VxFS file system due to a race condition on MP systems between VxFS and the buffer cache. PHKL_17624: ( SR: 5003443622 DTS: JAGaa43921 ) System appears to hang intermittently due to processes being deactivated by the scheduler. The symptom is particularly visible on Netscape servers or on systems running applications using large amount of mmap files. Patch PHKL_13155 which is supposed to address the exact problem is not enough to solve the deactivation. Defect Description: PHKL_18551: ( SR: 4701422873 DTS: JAGab11378 ) Buffer cache routines in the kernel are gradually consuming more cpu time as buffer hash queues become longer. Resolution: This problem is resolved by ensuring buffers associated with unlinked (or truncated) files are re-used immediately ensuring they do not accumulate on any particular link-list. PHKL_17714: ( SR: 1653286468 DTS: JAGaa44872 ) When a new buffer is obtained via getnewbuf(), the identity may change. However, some processes may be sleeping waiting on the original buffer identity, and these never wake up. Resolution: The fix is to wakeup any process sleeping on a buffer returned by getnewbuf() when it changes the buffer identity. PHKL_17624: ( SR: 5003443622 DTS: JAGaa43921 ) The scheduler determines the system is thrashing based on the pageout rate. However, for systems with large amount of mmap files, syncing these files to disk is a normal operation which generates very high pageout rate that has nothing to do with thrashing due to lack of free memory. Resolution: A kernel variable is added to decouple user (system call) and kernel (vhand) initiated pageouts. Thrashing determination is based on the kernel pageout only. SR: 1653286468 4701422873 5003443622 Patch Files: /usr/conf/lib/libhp-ux.a(vfs_bio.o) /usr/conf/lib/libhp-ux.a(vfs_vm.o) /usr/conf/lib/libhp-ux.a(vm_devswap.o) /usr/conf/lib/libhp-ux.a(vm_sched.o) /usr/conf/lib/libhp-ux.a(vm_swp.o) /usr/conf/lib/libhp-ux.a(vm_vhand.o) what(1) Output: /usr/conf/lib/libhp-ux.a(vfs_bio.o): vfs_bio.c $Date: 99/05/06 12:14:50 $ $Revision: 1.26 .98.31 $ PATCH_10.20 (PHKL_18551) /usr/conf/lib/libhp-ux.a(vfs_vm.o): vfs_vm.c $Date: 99/02/17 14:18:42 $ $Revision: 1.17. 98.19 $ PATCH_10.20 (PHKL_17624) /usr/conf/lib/libhp-ux.a(vm_devswap.o): vm_devswap.c $Date: 99/02/17 14:23:50 $ $Revision : 1.19.98.8 $ PATCH_10.20 (PHKL_17624) /usr/conf/lib/libhp-ux.a(vm_sched.o): vm_sched.c $Date: 99/02/17 14:24:58 $ $Revision: 1.58.98.13 $ PATCH_10.20 (PHKL_17624) /usr/conf/lib/libhp-ux.a(vm_swp.o): vm_swp.c $Date: 99/02/17 14:25:34 $ $Revision: 1. 49.98.4 $ PATCH_10.20 (PHKL_17624) /usr/conf/lib/libhp-ux.a(vm_vhand.o): vm_vhand.c $Date: 99/02/17 14:26:10 $ $Revision: 1.20.98.8 $ PATCH_10.20 (PHKL_17624) cksum(1) Output: 80256480 29684 /usr/conf/lib/libhp-ux.a(vfs_bio.o) 917183867 29828 /usr/conf/lib/libhp-ux.a(vfs_vm.o) 3031568726 15464 /usr/conf/lib/libhp-ux.a(vm_devswap.o) 4032129670 25200 /usr/conf/lib/libhp-ux.a(vm_sched.o) 1245976871 7848 /usr/conf/lib/libhp-ux.a(vm_swp.o) 2447548175 15072 /usr/conf/lib/libhp-ux.a(vm_vhand.o) Patch Conflicts: None Patch Dependencies: s700: 10.20: PHKL_16750 Hardware Dependencies: None Other Dependencies: None Supersedes: PHKL_17624 PHKL_17714 Equivalent Patches: None Patch Package Size: 190 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_18551 5a. For a standalone system, run swinstall to install the patch: swinstall -x autoreboot=true -x match_target=true \ -s /tmp/PHKL_18551.depot 5b. For a homogeneous NFS Diskless cluster run swcluster on the server to install the patch on the server and the clients: swcluster -i -b This will invoke swcluster in the interactive mode and force all clients to be shut down. WARNING: All cluster clients must be shut down prior to the patch installation. Installing the patch while the clients are booted is unsupported and can lead to serious problems. The swcluster command will invoke an swinstall session in which you must specify: alternate root path - default is /export/shared_root/OS_700 source depot path - /tmp/PHKL_18551.depot To complete the installation, select the patch by choosing "Actions -> Match What Target Has" and then "Actions -> Install" from the Menubar. 5c. For a heterogeneous NFS Diskless cluster: - run swinstall on the server as in step 5a to install the patch on the cluster server. - run swcluster on the server as in step 5b to install the patch on the cluster clients. By default swinstall will archive the original software in /var/adm/sw/patch/PHKL_18551. 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_18551.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: dd if=/tmp/PHKL_18551.depot of=/dev/rmt/0m bs=2k Special Installation Instructions: This patch depends on base patch PHKL_16750 . For successful installation please insure that PHKL_16750 is in the same depot with PHKL_18551, or PHKL_16750 is already installed.