Patch Name: PHKL_30516

Patch Description: s700_800 11.11 Buffercache performance; select_enh tunable

Creation Date: 04/05/06

Post Date: 04/08/20

Hardware Platforms - OS Releases:
	s700: 11.11
	s800: 11.11

Products: N/A

Filesets:
	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP
	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP
	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP
	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP

Automatic Reboot?: Yes

Status: General Release

Critical:
	No (superseded patches were critical)
	PHKL_29527: PANIC
	PHKL_27808: ABORT OTHER
		Possible ServiceGuard TOC. Performance
		degradation, slow response time, and high CPU
		utilization.

Category Tags:
	defect_repair general_release critical panic halts_system

Path Name: /hp-ux_patches/s700_800/11.X/PHKL_30516

Symptoms:
	PHKL_30516:
	( SR:8606351156 CR:JAGaf11968 )
	select(2) system call, with a timeout lesser than 10ms,
	takes a longer delay.

	PHKL_29527:
	( SR:8606326776 CR:JAGae89051 )
	Systems with 128GB or more of physical memory will panic
	with the patch PHKL_27808 installed. The stack trace similar
	to following will be observed on dump analysis:

	panic+0x6c
	fdc_target_miss_PCXU+0x1c
	T600_patch_07+0x0
	hdl_zero_page+0x110
	kalloc_from_superpage+0x2e0
	kalloc+0x14
	bminit+0x78
	binit+0x130
	DoCalllist+0x3c
	main+0x28
	$vstart+0x48
	istackatbase+0x84

	( SR:8606300949 CR:JAGae64419 )
	The number of buffers that can be allocated to the buffer
	cache is incorrectly calculated and thus buffer cache
	will be much smaller than reflected by dbc_max_pct.

	PHKL_27808:
	( SR:8606262741 CR:JAGae27072 )
	Performance   degradation,  slow  response  time,  high  CPU
	utilization, and potential  ServiceGuard TOC when performing
	I/O.

	PHKL_25886:
	( SR:8606217170 CR:JAGad86324 )
	I/O performance is very slow when reading/writing many
	VxFS filesystems at the same time.

Defect Description:
	PHKL_30516:
	( SR:8606351156 CR:JAGaf11968 )
	A File System tunable needs to be introduced for regulating
	a feature in select(2), which has been introduced by
	PHKL_30373.

	Resolution:
	Added 'select_enh', a File System dynamic tunable.  The
	default value of this tunable is 0.  There will be no impact
	on the system when the tunable is set to it's default value.
	PHKL_30373 provides the fix to reduce the delay taken by
	select(2) system call with an input timeout argument of 10
	ms.  This delay did not exist in 11.00, but was introduced
	in 11.11 LR.  So, this fix in PHKL_30373 could potentially
	affect many applications using select(2).  We are therefore,
	giving our customers the option of selecting the behaviour
	existing in 11.00 or 11.11 through the means of this tunable
	'select_enh'.  The fix present in PHKL_30373 will come into
	effect only when the value of 'select_enh' is set to 1.

	PHKL_29527:
	( SR:8606326776 CR:JAGae89051 )
	An internal variable defined as 32 bits overflowed
	causing an incorrect value set to the buffer cache
	bitmap size.

	Resolution:
	The data type for this variable has been changed to
	prevent the overflow condition.

	( SR:8606300949 CR:JAGae64419 )
	The minimum and maximum number of buffers calculated as
	a result of dbc_max_pct and dbc_min_pct can be incorrect
	on large memory systems (>256GB) due to an overflow
	of the data type used in the calculation.

	Resolution:
	The variable has been suitably typecasted to prevent
	the overflow during calculation.

	PHKL_27808:
	( SR:8606262741 CR:JAGae27072 )
	The performance  degradation is caused by  fragmentation  of
	the buffer cache  virtual map.  The  fragmentation  causes a
	process to perform exhausting searches for virtual addresses
	in the buffer cache to accommodate  the request.  PHKL_25886
	doubles  the  size  of the  buffer  cache  virtual  map  and
	resolves  most  of  these  fragmentation   issues.  However,
	PHKL_25886  does not account for varying  buffer sizes up to
	the maximum buffer size of 65536.

	Resolution:
	A new  tunable  was  added to help  size  the  buffer  cache
	virtual map:

	    Tunable                     Range           Default
	    bcvmap_size_factor          1..64           2

	Each bit in the buffer  cache  virtual  map  represents  one
	page.  Configuring  a larger  buffer cache  virtual map will
	reduce  fragmentation  since more virtual addresses are made
	available.  The size of the bitmap is calculated as follows:

	        bcvmap_sz (in bits) = physical_memory_pages *
	                                         bcvmap_size_factor

	Setting  bcvmap_size_factor to 2 (default) is sufficient for
	most  systems  and  will  yield  the  same  results  as  the
	superseded  patch  PHKL_25886.  If a large  buffer  cache is
	used  (dbc_max_pct  > 50%) and buffers  larger  than 8KB are
	used, then  bcvmap_size_factor  should be configured larger.
	Buffers  larger than 8KB are used with HFS file systems with
	a block size > 8KB, and with JFS file systems if the tunable
	max_buf_data_size   is  set  to  65536  (see  vxtunefs(1M)).
	Configuring  bcvmap_size_factor  outside the supported range
	(1..64) will result in adjusting the variable to the closest
	supported  range.  This new tunable is available  only on 64
	bit systems as the size of buffer cache virtual map is fixed
	on 32 bit systems.

	PHKL_25886:
	( SR:8606217170 CR:JAGad86324 )
	I/O perforamce degrades when buffercache usage is high.
	There are several reasons for this.  The main reason is
	virtual address map size.  The next is that upon creation,
	the buffercache headers are not marked invalid, so they do
	not get used immediately.  The third is that the method of
	virtual address allocation is not optimal.

	Resolution:
	Increase the default virtual address map size to be double
	the physical memory.

	Initialize the buffercache headers as invalid to ensure
	immediate use.

	Modify the buffercache address allocation routines to remove
	bitmap groups from active queue when they are migrated to
	the low state.

Enhancement:
	No

SR:
	8606217170 8606262741 8606300949 8606326776 8606351156

Patch Files:
	
	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	/usr/conf/lib/libfs-pdk.a(bcvalloc.o)
	/usr/conf/lib/libfs-pdk.a(ufs_mchdep.o)
	/usr/conf/lib/libfs.a(dbc_bio.o)
	/usr/conf/lib/libfs.a(fs_tunables.o)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	/usr/conf/master.d/fs-tune
	/usr/conf/space.h.d/fs-tune.h

	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	/usr/conf/lib/libfs-pdk.a(bcvalloc.o)
	/usr/conf/lib/libfs-pdk.a(ufs_mchdep.o)
	/usr/conf/lib/libfs.a(dbc_bio.o)
	/usr/conf/lib/libfs.a(fs_tunables.o)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	/usr/conf/master.d/fs-tune
	/usr/conf/space.h.d/fs-tune.h

what(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	/usr/conf/lib/libfs-pdk.a(bcvalloc.o):
		bcvalloc.c $Date: 2002/01/30 13:53:59 $Revision: r11
			.11/1 PATCH_11.11 (PHKL_25886)
	/usr/conf/lib/libfs-pdk.a(ufs_mchdep.o):
		ufs_mchdep.c $Date: 2003/09/27 09:49:32 $Revision: r
			11.11/4 PATCH_11.11 (PHKL_29527)
	/usr/conf/lib/libfs.a(dbc_bio.o):
		dbc_bio.c $Date: 2003/07/30 12:15:40 $Revision: r11.
			11/1 PATCH_11.11 (PHKL_29527)
	/usr/conf/lib/libfs.a(fs_tunables.o):
		fs_tunables.c $Date: 2004/04/06 23:01:04 $Revision: 
			r11.11/1 PATCH_11.11 (PHKL_30516)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	/usr/conf/master.d/fs-tune:
		fs-tune $Date: 2004/04/06 23:11:48 $Revision: r11.11
			/1 PATCH_11.11 (PHKL_30516)
	/usr/conf/space.h.d/fs-tune.h:
		fs-tune.h $Date: 2004/04/06 23:06:22 $Revision: r11.
			11/1 PATCH_11.11 (PHKL_30516) */

	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	/usr/conf/lib/libfs-pdk.a(bcvalloc.o):
		bcvalloc.c $Date: 2002/01/30 13:53:59 $Revision: r11
			.11/1 PATCH_11.11 (PHKL_25886)
	/usr/conf/lib/libfs-pdk.a(ufs_mchdep.o):
		ufs_mchdep.c $Date: 2003/09/27 09:49:32 $Revision: r
			11.11/4 PATCH_11.11 (PHKL_29527)
	/usr/conf/lib/libfs.a(dbc_bio.o):
		dbc_bio.c $Date: 2003/07/30 12:15:40 $Revision: r11.
			11/1 PATCH_11.11 (PHKL_29527)
	/usr/conf/lib/libfs.a(fs_tunables.o):
		fs_tunables.c $Date: 2004/04/06 23:01:04 $Revision: 
			r11.11/1 PATCH_11.11 (PHKL_30516)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	/usr/conf/master.d/fs-tune:
		fs-tune $Date: 2004/04/06 23:18:17 $Revision: r11.11
			/3 PATCH_11.11 (PHKL_30516)
	/usr/conf/space.h.d/fs-tune.h:
		fs-tune.h $Date: 2004/04/06 23:09:17 $Revision: r11.
			11/3 PATCH_11.11 (PHKL_30516) */

cksum(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	2589179789 5056 /usr/conf/lib/libfs-pdk.a(bcvalloc.o)
	1613527565 12276 /usr/conf/lib/libfs-pdk.a(ufs_mchdep.o)
	2298367487 6284 /usr/conf/lib/libfs.a(dbc_bio.o)
	2179595901 3980 /usr/conf/lib/libfs.a(fs_tunables.o)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
	202868130 2798 /usr/conf/master.d/fs-tune
	1295681042 5231 /usr/conf/space.h.d/fs-tune.h

	OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	849287225 10808 /usr/conf/lib/libfs-pdk.a(bcvalloc.o)
	163004609 28232 /usr/conf/lib/libfs-pdk.a(ufs_mchdep.o)
	3828622684 13880 /usr/conf/lib/libfs.a(dbc_bio.o)
	3162279165 6624 /usr/conf/lib/libfs.a(fs_tunables.o)

	OS-Core.KERN2-RUN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
	3049481409 2906 /usr/conf/master.d/fs-tune
	1062970469 5556 /usr/conf/space.h.d/fs-tune.h

Patch Conflicts: None

Patch Dependencies: None

Hardware Dependencies: None

Other Dependencies: None

Supersedes:
	PHKL_29527 PHKL_27808 PHKL_25886

Equivalent Patches: None

Patch Package Size: 90 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_30516

	5. Run swinstall to install the patch:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -s /tmp/PHKL_30516.depot

	By default swinstall will archive the original software in 
	/var/adm/sw/save/PHKL_30516.  If you do not wish to retain a
	copy of the original software, include the patch_save_files
	option in the swinstall command above:

		-x patch_save_files=false

	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_30516.text file is 
	available in the product readme:

		swlist -l product -a readme -d @ /tmp/PHKL_30516.depot

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

		dd if=/tmp/PHKL_30516.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions: None