kernel-ark/lib
Paul Jackson 7ea931c9fc mempolicy: add bitmap_onto() and bitmap_fold() operations
The following adds two more bitmap operators, bitmap_onto() and bitmap_fold(),
with the usual cpumask and nodemask wrappers.

The bitmap_onto() operator computes one bitmap relative to another.  If the
n-th bit in the origin mask is set, then the m-th bit of the destination mask
will be set, where m is the position of the n-th set bit in the relative mask.

The bitmap_fold() operator folds a bitmap into a second that has bit m set iff
the input bitmap has some bit n set, where m == n mod sz, for the specified sz
value.

There are two substantive changes between this patch and its
predecessor bitmap_relative:
 1) Renamed bitmap_relative() to be bitmap_onto().
 2) Added bitmap_fold().

The essential motivation for bitmap_onto() is to provide a mechanism for
converting a cpuset-relative CPU or Node mask to an absolute mask.  Cpuset
relative masks are written as if the current task were in a cpuset whose CPUs
or Nodes were just the consecutive ones numbered 0..N-1, for some N.  The
bitmap_onto() operator is provided in anticipation of adding support for the
first such cpuset relative mask, by the mbind() and set_mempolicy() system
calls, using a planned flag of MPOL_F_RELATIVE_NODES.  These bitmap operators
(and their nodemask wrappers, in particular) will be used in code that
converts the user specified cpuset relative memory policy to a specific system
node numbered policy, given the current mems_allowed of the tasks cpuset.

Such cpuset relative mempolicies will address two deficiencies
of the existing interface between cpusets and mempolicies:
 1) A task cannot at present reliably establish a cpuset
    relative mempolicy because there is an essential race
    condition, in that the tasks cpuset may be changed in
    between the time the task can query its cpuset placement,
    and the time the task can issue the applicable mbind or
    set_memplicy system call.
 2) A task cannot at present establish what cpuset relative
    mempolicy it would like to have, if it is in a smaller
    cpuset than it might have mempolicy preferences for,
    because the existing interface only allows specifying
    mempolicies for nodes currently allowed by the cpuset.

Cpuset relative mempolicies are useful for tasks that don't distinguish
particularly between one CPU or Node and another, but only between how many of
each are allowed, and the proper placement of threads and memory pages on the
various CPUs and Nodes available.

The motivation for the added bitmap_fold() can be seen in the following
example.

Let's say an application has specified some mempolicies that presume 16 memory
nodes, including say a mempolicy that specified MPOL_F_RELATIVE_NODES (cpuset
relative) nodes 12-15.  Then lets say that application is crammed into a
cpuset that only has 8 memory nodes, 0-7.  If one just uses bitmap_onto(),
this mempolicy, mapped to that cpuset, would ignore the requested relative
nodes above 7, leaving it empty of nodes.  That's not good; better to fold the
higher nodes down, so that some nodes are included in the resulting mapped
mempolicy.  In this case, the mempolicy nodes 12-15 are taken modulo 8 (the
weight of the mems_allowed of the confining cpuset), resulting in a mempolicy
specifying nodes 4-7.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: <kosaki.motohiro@jp.fujitsu.com>
Cc: <ray-lk@madrabbit.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 08:58:19 -07:00
..
lzo lzo: fix typo in decompressor 2008-04-10 15:34:05 -07:00
reed_solomon lib: Remove unnecessary inclusions of asm/semaphore.h 2008-04-18 22:17:17 -04:00
zlib_deflate lib/: Spelling fixes 2008-02-03 17:48:52 +02:00
zlib_inflate [ZLIB]: Fix external builds of zlib_inflate code. 2007-10-11 22:17:20 -07:00
.gitignore
argv_split.c LIB: Replace inappropriate include of <linux/bug.h> 2007-10-20 00:26:10 +02:00
audit.c
bitmap.c mempolicy: add bitmap_onto() and bitmap_fold() operations 2008-04-28 08:58:19 -07:00
bitrev.c
bug.c
bust_spinlocks.c handle recursive calls to bust_spinlocks() 2007-10-17 08:42:56 -07:00
check_signature.c
cmdline.c
cpumask.c
crc7.c
crc16.c
crc32.c lib/: Spelling fixes 2008-02-03 17:48:52 +02:00
crc32defs.h
crc-ccitt.c
crc-itu-t.c
ctype.c
debug_locks.c
dec_and_lock.c
devres.c devres: implement pcim_iomap_regions_request_all() 2008-03-17 08:26:44 -04:00
div64.c
dump_stack.c
extable.c lib/extable.c: remove an expensive integer divide in search_extable() 2008-02-06 10:41:08 -08:00
fault-inject.c libfs: allow error return from simple attributes 2008-02-08 09:22:34 -08:00
find_next_bit.c x86: generic versions of find_first_(zero_)bit, convert i386 2008-04-26 19:21:16 +02:00
gen_crc32table.c
genalloc.c
halfmd4.c
hexdump.c hexdump: don't print bytes with bit 7 set 2007-11-29 09:24:53 -08:00
hweight.c remove asm/bitops.h includes 2007-10-19 11:53:41 -07:00
idr.c Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
inflate.c
int_sqrt.c
iomap_copy.c
iomap.c x86-32: Pass the full resource data to ioremap() 2008-03-24 11:22:39 -07:00
iommu-helper.c iommu: export iommu_is_span_boundary helper function 2008-03-04 16:35:17 -08:00
ioremap.c lib/ioremap.c should #include <linux/io.h> 2007-10-17 08:42:50 -07:00
irq_regs.c
kasprintf.c lib: move kasprintf to a separate file 2007-07-31 15:39:39 -07:00
Kconfig x86, bitops: select the generic bitmap search functions 2008-04-26 19:21:17 +02:00
Kconfig.debug Add option to enable -Wframe-larger-than= on gcc 4.4 2008-04-25 20:23:47 +02:00
Kconfig.kgdb kgdb: allow static kgdbts boot configuration 2008-04-17 20:05:43 +02:00
kernel_lock.c Convert asm/semaphore.h users to linux/semaphore.h 2008-04-18 22:22:54 -04:00
klist.c
kobject_uevent.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-04-03 14:33:42 -07:00
kobject.c Kobject: Replace list_for_each() with list_for_each_entry(). 2008-04-19 19:10:27 -07:00
kref.c kref: add kref_set() 2008-01-24 20:40:05 -08:00
libcrc32c.c [LIB] crc32c: Keep intermediate crc state in cpu order 2007-11-08 21:34:09 +08:00
list_debug.c
lmb.c [LMB]: Fix lmb allocation regression. 2008-04-23 23:30:59 -07:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c
Makefile x86: generic versions of find_first_(zero_)bit, convert i386 2008-04-26 19:21:16 +02:00
parser.c
percpu_counter.c Add irq protection in the percpu-counters cpu-hotplug-callback path 2007-10-19 11:53:44 -07:00
plist.c
prio_heap.c Fix cpusets update_cpumask 2007-10-19 11:53:41 -07:00
prio_tree.c
proportions.c lib: proportion: fix underflow in prop_norm_percpu() 2007-12-23 12:54:37 -08:00
radix-tree.c Remove set_migrateflags() 2008-04-28 08:58:17 -07:00
random32.c [NET]: srandom32 fixes for networking v2 2008-04-03 14:07:02 -07:00
rbtree.c
reciprocal_div.c
rwsem-spinlock.c lib: remove fastcall from lib/* 2008-02-08 09:22:31 -08:00
rwsem.c x86: fix UML and -regparm=3 2008-01-30 13:33:00 +01:00
scatterlist.c [SCSI] block: add sg buffer copy helper functions 2008-04-07 12:15:45 -05:00
sha1.c
smp_processor_id.c debug_smp_processor_id() fixlets 2008-02-06 10:41:09 -08:00
sort.c lib/sort.c optimization 2007-10-17 08:42:52 -07:00
spinlock_debug.c Use helpers to obtain task pid in printks 2007-10-19 11:53:43 -07:00
string.c
swiotlb.c avoid endless loops in lib/swiotlb.c 2008-03-13 13:15:52 -07:00
textsearch.c [TEXTSEARCH]: Do not allow zero length patterns in the textsearch infrastructure 2007-12-01 00:03:52 +11:00
ts_bm.c
ts_fsm.c
ts_kmp.c
vsprintf.c lib/vsprintf.c: fix bug omitting minus sign of numbers (module_param) 2008-02-23 17:12:14 -08:00