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Fix the default behaviour for the remap operators in bitmap, cpumask and
nodemask.
As previously submitted, the pair of masks <A, B> defined a map of the
positions of the set bits in A to the corresponding bits in B. This is still
true.
The issue is how to map the other positions, corresponding to the unset (0)
bits in A. As previously submitted, they were all mapped to the first set bit
position in B, a constant map.
When I tried to code per-vma mempolicy rebinding using these remap operators,
I realized this was wrong.
This patch changes the default to map all the unset bit positions in A to the
same positions in B, the identity map.
For example, if A has bits 4-7 set, and B has bits 9-12 set, then the map
defined by the pair <A, B> maps each bit position in the first 32 bits as
follows:
0 ==> 0
...
3 ==> 3
4 ==> 9
...
7 ==> 12
8 ==> 8
9 ==> 9
...
31 ==> 31
This now corresponds to the typical behaviour desired when migrating pages and
policies from one cpuset to another.
The pages on nodes within the original cpuset, and the references in memory
policies to nodes within the original cpuset, are migrated to the
corresponding cpuset-relative nodes in the destination cpuset. Other pages
and node references are left untouched.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In the forthcoming task migration support, a key calculation will be
mapping cpu and node numbers from the old set to the new set while
preserving cpuset-relative offset.
For example, if a task and its pages on nodes 8-11 are being migrated to
nodes 24-27, then pages on node 9 (the 2nd node in the old set) should be
moved to node 25 (the 2nd node in the new set.)
As with other bitmap operations, the proper way to code this is to provide
the underlying calculation in lib/bitmap.c, and then to provide the usual
cpumask and nodemask wrappers.
This patch provides that. These operations are termed 'remap' operations.
Both remapping a single bit and a set of bits is supported.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch makes use of ALIGN() to remove duplicate round-up code.
Signed-off-by: Nick Wilson <njw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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[This is a copy of the bitmap list format patch that I submitted to lkml
on 9 Aug 2004, after removing the prefix character fluff^Wstuff. I
include it here again just to get it associated with the current cpuset
patch, which will follow in a second email 10 seconds later. -pj]
A bitmap print and parse format that provides lists of ranges of numbers,
to be first used for by cpusets (next patch).
Cpusets provide a way to manage subsets of CPUs and Memory Nodes for
scheduling and memory placement, via a new virtual file system, usually
mounted at /dev/cpuset. Manipulation of cpusets can be done directly via
this file system, from the shell.
However, manipulating 512 bit cpumasks or 256 bit nodemasks (which will get
bigger) via hex mask strings is painful for humans.
The intention is to provide a format for the cpu and memory mask files in
/dev/cpusets that will stand the test of time. This format is supported by
a couple of new lib/bitmap.c routines, for printing and parsing these
strings. Wrappers for cpumask and nodemask are provided.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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There's no reason to directly #include <asm/bitops.h> since it's
available on all architectures and also included by
#include <linux/bitops.h>.
This patch changes #include <asm/bitops.h> to #include <linux/bitops.h>.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Bug spotted by: Ian Molton <spyro@f2s.com>
BITS_TO_LONGS() can't be used to derive an index
into a bitmap array.
Also put a BUG_ON() for the pages > BITS_PER_LONG case
we don't cope with.
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These APIs deal with bitmaps representing contiguous
memory regions. The idea is to set, free and find
a contiguous area.
For ease of implementation (as well as to conform
to the standard requirements), the bitmaps always
return n aligned n length regions. The implementation
is also limited to BITS_PER_LONG contiguous regions.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
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From: Paul Jackson <pj@sgi.com>
These bitmap improvements make it a suitable basis for fully supporting
cpumask_t and nodemask_t. Inline macros with compile-time checks enable
generating tight code on both small and large systems (large meaning cpumask_t
requires more than one unsigned long's worth of bits).
The existing bitmap_<op> macros in lib/bitmap.c are renamed to __bitmap_<op>,
and wrappers for each bitmap_<op> are exposed in include/linux/bitmap.h
This patch _includes_ Bill Irwins rewrite of the bitmap_shift operators to not
require a fixed length intermediate bitmap.
Improved comments list each available operator for easy browsing.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Paul Jackson <pj@sgi.com>
Document the bitmap bit model and handling of unused bits.
Tighten up bitmap so it does not generate nonzero bits in the unused tail if
it is not given any on input.
Add intersects, subset, xor and andnot operators. Change bitmap_complement to
take two operands.
Add a couple of missing 'const' qualifiers on bitops test_bit and bitmap_equal
args.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Rusty Russell <rusty@rustcorp.com.au>
clear_bit(n, addr) clears the nth bit.
test_and_clear_bit(n, addr) clears the nth bit.
cpu_clear(n, cpumask) clears the nth bit (vs. cpus_clear()).
bitmap_clear(bitmap, n) clears out all the bits up to n.
Moreover, there's a CLEAR_BITMAP() in linux/types.h which bitmap_clear() is
a wrapper for.
Rename bitmap_clear to bitmap_zero, which is harder to confuse (yes, it bit
me), and make everyone use it.
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From: William Lee Irwin III <wli@holomorphy.com>
Chang bitmap_shift_left()/bitmap_shift_right() to have O(1) stackspace
requirements.
Given zeroed tail preconditions these implementations satisfy zeroed tail
postconditions, which makes them compatible with whatever changes from Paul
Jackson one may want to merge in the future. No particular effort was
required to ensure this.
A small (but hopefully forgiveable) cleanup is a spelling correction:
s/bitmap_shift_write/bitmap_shift_right/ in one of the kerneldoc comments.
The primary effect of the patch is to remove the MAX_BITMAP_BITS
limitation, so restoring the NR_CPUS to be limited only by stackspace and
slab allocator maximums. They also look vaguely more efficient than the
current code, though as this was not done for performance reasons, no
performance testing was done.
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From: Joe Korty <joe.korty@ccur.com>
This patch replaces the call to bitmap_shift_right() in bitmap_parse() with
bitmap_shift_left().
I also prepended comments to the bitmap_shift_* functions defining what
'left' and 'right' means. This is under the theory that if I and all the
reviewers were bamboozled, others in the future occasionally might be too.
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This cleans up a larger amount of superfluos ";;" statements in current
Linux kernel sources by converting them to the regular single ";"
statments.
It seems to be a common problem that at the end of a line the semicolon
key is producing an echo.
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From: Joe Korty <joe.korty@ccur.com>
Rename bitmap_snprintf() to bitmap_scnprintf() and cpumask_snprintf() to
cpumask_scnprintf(), as these functions now belong to the scnprintf family
of functions.
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From: Juergen Quade <quade@hsnr.de>
Lots of places in the kernel are using [v]snprintf wrongly: they assume it
returns the number of characters copied. It doesn't. It returns the
number of characters which _would_ have been copied had the buffer not been
filled up.
So create new functions vscnprintf() and scnprintf() which have the
expected (sane) semaptics, and migrate callers over to using them.
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From: Joe Korty <joe.korty@ccur.com>
Now that bitmap_parse is part of bitmap.[ch], it is allowed to manipulate
bits directly as the other bitmap routines do.
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From: Joe Korty <joe.korty@ccur.com>
1) the version in 2.6.1 is broken, doesn't work on 64bit big endian
machines at all. This needed fixing. I thought it best to fix by
rewriting the printer/parser with an algorithm that is naturally endian &
sizeof(long) resistant.
2) I wanted all digits to print, eg, 0000ffff,00000004 not ffff,4.
3) I wanted exactly NR_CPUS bits to print (or whatever the bitmap size is
in bits, and not have what is displayed rounded up to the nearest full
byte, as the current version did.
4) The bitmap printer and parser should be part of bitmap.[ch] with syntax
and semantics to match. The original lib/mask.c versions did not
recognize this commonality.
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gcc miscompiles this. Scary.
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- A couple of them are using alloca (via DECLARE_BITMAP) and this generates
a cannot-inline warning with -Winline.
- These functions are too big to inline anwyay.
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