Patch Name: PHKL_21549

Patch Description: s700_800 11.00 Cumulative gang scheduling patch

Creation Date: 00/04/14

Post Date:  00/04/19

Hardware Platforms - OS Releases:
	s700: 11.00
	s800: 11.00

Products: N/A

Filesets:
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP

Automatic Reboot?: Yes

Status: General Release

Critical:
	Yes
	PHKL_21549: HANG

Category Tags:
	defect_repair general_release critical halts_system

Path Name: /hp-ux_patches/s700_800/11.X/PHKL_21549

Symptoms:
	PHKL_21549:
	( SR: 8606129909 DTS: JAGac88824 )
	Gang scheduled applications appear to hang or
	make minimal forward progress.

	PHKL_19315:
	( SR: 1653280479 DTS: JAGaa42348 )
	CPU usage of a mult-threaded job with gang-scheduling
	on is reduced drasticly while a single-threaded job
	with higher priority is running.

Defect Description:
	PHKL_21549:
	( SR: 8606129909 DTS: JAGac88824 )
	The gang scheduler did not recognize a new cpu state
	that was added to the system initialization process.
	This resulted in all gang scheduled processes being
	bound to the monarch processor.

	Resolution:
	At system initialization the gang scheduler now
	takes into account the new cpu state and uses all
	available processors instead of just the monarch.

	PHKL_19315:
	( SR: 1653280479 DTS: JAGaa42348 )
	The GANG scheduling of multithreaded applications allows
	users to improve significantly the performance of their jobs
	that run on a subset of processors.

	In an enviroment that uses different priorities for the
	jobs, over-subscription becomes a problem: A singlethreaded
	job of high priority is able to reduce the CPU usage of all
	running multithreaded jobs. The expectation is that the
	singlethreaded job reduces in average the CPU usage of one
	gang independently from the priority of the singlethreaded
	job.

	Resolution:
	This patch to the gang scheduler removes a previous change
	that corrects the fairness algorithm of the gang scheduler
	load balancer.  The code is reverted back to its original
	algorithm for when to initiate the gang scheduler load
	balancer.  Balancing is not performed is we are under or
	completely subscribed.  Only when the active gangs
	oversubscribe the available processors will the load
	balancer be initiated.

SR:
	1653280479 8606129909

Patch Files:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	/usr/conf/lib/libhp-ux.a(pm_gang.o)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	/usr/conf/lib/libhp-ux.a(pm_gang.o)

what(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	/usr/conf/lib/libhp-ux.a(pm_gang.o):
		pm_gang.c $Date: 2000/04/14 11:31:10 $Revision: r11r
			os/7 PATCH_11.00 (PHKL_21549)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	/usr/conf/lib/libhp-ux.a(pm_gang.o):
		pm_gang.c $Date: 2000/04/14 11:31:10 $Revision: r11r
			os/7 PATCH_11.00 (PHKL_21549)

cksum(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	1504056914 16644 /usr/conf/lib/libhp-ux.a(pm_gang.o)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	3748670825 45896 /usr/conf/lib/libhp-ux.a(pm_gang.o)

Patch Conflicts: None

Patch Dependencies:
	s700: 11.00: PHKL_18543
	s800: 11.00: PHKL_18543

Hardware Dependencies: None

Other Dependencies: None

Supersedes:
	PHKL_19315 

Equivalent Patches: None

Patch Package Size: 100 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_21549

	5. Run swinstall to install the patch:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -s /tmp/PHKL_21549.depot

	By default swinstall will archive the original software in 
	/var/adm/sw/save/PHKL_21549.  If you do not wish to retain a
	copy of the original software, use the patch_save_files option:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -x patch_save_files=false -s /tmp/PHKL_21549.depot

	WARNING: If patch_save_files is false when a patch is installed,
		 the patch cannot be deinstalled.  Please be careful
		 when using this feature.

	For future reference, the contents of the PHKL_21549.text file is 
	available in the product readme:

		swlist -l product -a readme -d @ /tmp/PHKL_21549.depot

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

		dd if=/tmp/PHKL_21549.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions:
	This patch depends on base patch PHKL_18543.
	For successful installation please insure that PHKL_18543
	is already installed, or that PHKL_18543 is included
	in the same depot with this patch and PHKL_18543
	is selected for installation.