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Subject[PATCH 17/35] cpumask: make nr_cpu_ids the actual limit on bitmap size
nr_cpu_ids is the (badly named) runtime limit on possible CPU numbers;
ie. the variable version of NR_CPUS.

If we use this in *all* the cpu ops it simplifies the API, and will
be possible to allocate cpumasks of the minimal length at runtime.

From: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
---
include/linux/cpumask.h | 124 ++++++++++++++++++-----------------------------
include/linux/seq_file.h | 2
lib/cpumask.c | 14 +----
3 files changed, 54 insertions(+), 86 deletions(-)

--- linux-2.6.28.orig/include/linux/cpumask.h
+++ linux-2.6.28/include/linux/cpumask.h
@@ -3,7 +3,8 @@

/*
* Cpumasks provide a bitmap suitable for representing the
- * set of CPU's in a system, one bit position per CPU number.
+ * set of CPU's in a system, one bit position per CPU number up to
+ * nr_cpu_ids (<= NR_CPUS).
*
* Old-style uses "cpumask_t", but new ops are "struct cpumask *";
* don't put "struct cpumask"s on the stack.
@@ -20,20 +21,6 @@
* For details of cpumask_onto(), see bitmap_onto in lib/bitmap.c.
* For details of cpumask_fold(), see bitmap_fold in lib/bitmap.c.
*
- * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- * Note: The alternate operations with the suffix "_nr" are used
- * to limit the range of the loop to nr_cpu_ids instead of
- * NR_CPUS when NR_CPUS > 64 for performance reasons.
- * If NR_CPUS is <= 64 then most assembler bitmask
- * operators execute faster with a constant range, so
- * the operator will continue to use NR_CPUS.
- *
- * Another consideration is that nr_cpu_ids is initialized
- * to NR_CPUS and isn't lowered until the possible cpus are
- * discovered (including any disabled cpus). So early uses
- * will span the entire range of NR_CPUS.
- * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- *
* The available cpumask operations are:
*
* void cpumask_set_cpu(cpu, mask) turn on bit 'cpu' in mask
@@ -55,14 +42,12 @@
* int cpumask_empty(mask) Is mask empty (no bits sets)?
* int cpumask_full(mask) Is mask full (all bits sets)?
* int cpumask_weight(mask) Hamming weigh - number of set bits
- * int cpumask_weight_nr(mask) Same using nr_cpu_ids instead of NR_CPUS
*
* void cpumask_shift_right(dst, src, n) Shift right
* void cpumask_shift_left(dst, src, n) Shift left
*
- * int first_cpu(mask) Number lowest set bit, or NR_CPUS
- * int next_cpu(cpu, mask) Next cpu past 'cpu', or NR_CPUS
- * int next_cpu_nr(cpu, mask) Next cpu past 'cpu', or nr_cpu_ids
+ * int first_cpu(mask) Number lowest set bit, or >= nr_cpu_ids
+ * int next_cpu(cpu, mask) Next cpu past 'cpu', or >= nr_cpu_ids
*
* void cpumask_copy(dmask, smask) dmask = smask
*
@@ -113,8 +98,7 @@
* void cpumask_onto(dst, orig, relmap) *dst = orig relative to relmap
* void cpumask_fold(dst, orig, sz) dst bits = orig bits mod sz
*
- * for_each_cpu_mask(cpu, mask) for-loop cpu over mask using NR_CPUS
- * for_each_cpu_mask_nr(cpu, mask) for-loop cpu over mask using nr_cpu_ids
+ * for_each_cpu_mask(cpu, mask) for-loop cpu over mask using nr_cpu_ids
* for_each_cpu_mask_and(cpu, mask, and) for-loop cpu over (mask & and).
*
* int num_online_cpus() Number of online CPUs
@@ -150,7 +134,7 @@ struct cpumask {
};
#define cpumask_bits(maskp) ((maskp)->bits)

-#define cpumask_size() (BITS_TO_LONGS(NR_CPUS) * sizeof(long))
+#define cpumask_size() (BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long))

/* Deprecated. */
typedef struct cpumask cpumask_t;
@@ -188,6 +172,9 @@ extern cpumask_t _unused_cpumask_arg_;
#define cpus_fold(dst, orig, sz) \
cpumask_fold(&(dst), &(orig), sz)
#define cpus_addr(src) ((src).bits)
+#define next_cpu_nr(n, src) next_cpu(n, src)
+#define cpus_weight_nr(cpumask) cpus_weight(cpumask)
+#define for_each_cpu_mask_nr(cpu, mask) for_each_cpu_mask(cpu, mask)
/* End deprecated region. */

#if NR_CPUS > 1
@@ -225,73 +212,73 @@ static inline int cpumask_test_and_set_c

static inline void cpumask_setall(struct cpumask *dstp)
{
- bitmap_fill(dstp->bits, NR_CPUS);
+ bitmap_fill(dstp->bits, nr_cpumask_bits);
}

static inline void cpumask_clear(struct cpumask *dstp)
{
- bitmap_zero(dstp->bits, NR_CPUS);
+ bitmap_zero(dstp->bits, nr_cpumask_bits);
}

static inline void cpumask_and(struct cpumask *dstp,
const struct cpumask *src1p,
const struct cpumask *src2p)
{
- bitmap_and(dstp->bits, src1p->bits, src2p->bits, NR_CPUS);
+ bitmap_and(dstp->bits, src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline void cpumask_or(struct cpumask *dstp, const struct cpumask *src1p,
const struct cpumask *src2p)
{
- bitmap_or(dstp->bits, src1p->bits, src2p->bits, NR_CPUS);
+ bitmap_or(dstp->bits, src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline void cpumask_xor(struct cpumask *dstp,
const struct cpumask *src1p,
const struct cpumask *src2p)
{
- bitmap_xor(dstp->bits, src1p->bits, src2p->bits, NR_CPUS);
+ bitmap_xor(dstp->bits, src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline void cpumask_andnot(struct cpumask *dstp,
const struct cpumask *src1p,
const struct cpumask *src2p)
{
- bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, NR_CPUS);
+ bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline void cpumask_complement(struct cpumask *dstp,
const struct cpumask *srcp)
{
- bitmap_complement(dstp->bits, srcp->bits, NR_CPUS);
+ bitmap_complement(dstp->bits, srcp->bits, nr_cpumask_bits);
}

static inline int cpumask_equal(const struct cpumask *src1p,
const struct cpumask *src2p)
{
- return bitmap_equal(src1p->bits, src2p->bits, NR_CPUS);
+ return bitmap_equal(src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline int cpumask_intersects(const struct cpumask *src1p,
const struct cpumask *src2p)
{
- return bitmap_intersects(src1p->bits, src2p->bits, NR_CPUS);
+ return bitmap_intersects(src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline int cpumask_subset(const struct cpumask *src1p,
const struct cpumask *src2p)
{
- return bitmap_subset(src1p->bits, src2p->bits, NR_CPUS);
+ return bitmap_subset(src1p->bits, src2p->bits, nr_cpumask_bits);
}

static inline int cpumask_empty(const struct cpumask *srcp)
{
- return bitmap_empty(srcp->bits, NR_CPUS);
+ return bitmap_empty(srcp->bits, nr_cpumask_bits);
}

static inline int cpumask_full(const struct cpumask *srcp)
{
- return bitmap_full(srcp->bits, NR_CPUS);
+ return bitmap_full(srcp->bits, nr_cpumask_bits);
}

static inline int __cpus_weight(const cpumask_t *srcp, int nbits)
@@ -301,49 +288,49 @@ static inline int __cpus_weight(const cp

static inline int cpumask_weight(const struct cpumask *srcp)
{
- return bitmap_weight(srcp->bits, NR_CPUS);
+ return bitmap_weight(srcp->bits, nr_cpumask_bits);
}

static inline void cpumask_shift_right(struct cpumask *dstp,
const struct cpumask *srcp, int n)
{
- bitmap_shift_right(dstp->bits, srcp->bits, n, NR_CPUS);
+ bitmap_shift_right(dstp->bits, srcp->bits, n, nr_cpumask_bits);
}

static inline void cpumask_shift_left(struct cpumask *dstp,
const struct cpumask *srcp, int n)
{
- bitmap_shift_left(dstp->bits, srcp->bits, n, NR_CPUS);
+ bitmap_shift_left(dstp->bits, srcp->bits, n, nr_cpumask_bits);
}

static inline int cpumask_scnprintf(char *buf, int len,
const struct cpumask *srcp)
{
- return bitmap_scnprintf(buf, len, srcp->bits, NR_CPUS);
+ return bitmap_scnprintf(buf, len, srcp->bits, nr_cpumask_bits);
}

static inline int cpumask_parse_user(const char __user *buf, int len,
struct cpumask *dstp)
{
- return bitmap_parse_user(buf, len, dstp->bits, NR_CPUS);
+ return bitmap_parse_user(buf, len, dstp->bits, nr_cpumask_bits);
}

static inline int cpulist_scnprintf(char *buf, int len,
const struct cpumask *srcp)
{
- return bitmap_scnlistprintf(buf, len, srcp->bits, NR_CPUS);
+ return bitmap_scnlistprintf(buf, len, srcp->bits, nr_cpumask_bits);
}

static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
{
- return bitmap_parselist(buf, dstp->bits, NR_CPUS);
+ return bitmap_parselist(buf, dstp->bits, nr_cpumask_bits);
}

static inline int cpumask_cpuremap(int oldbit,
const struct cpumask *oldp,
const struct cpumask *newp)
{
- return bitmap_bitremap(oldbit, oldp->bits, newp->bits, NR_CPUS);
+ return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nr_cpumask_bits);
}

static inline void cpumask_remap(struct cpumask *dstp,
@@ -351,26 +338,27 @@ static inline void cpumask_remap(struct
const struct cpumask *oldp,
const struct cpumask *newp)
{
- bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, NR_CPUS);
+ bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits,
+ nr_cpumask_bits);
}

static inline void cpumask_onto(struct cpumask *dstp,
const struct cpumask *origp,
const struct cpumask *relmapp)
{
- bitmap_onto(dstp->bits, origp->bits, relmapp->bits, NR_CPUS);
+ bitmap_onto(dstp->bits, origp->bits, relmapp->bits, nr_cpumask_bits);
}

static inline void cpumask_fold(struct cpumask *dstp,
const struct cpumask *origp, int sz)
{
- bitmap_fold(dstp->bits, origp->bits, sz, NR_CPUS);
+ bitmap_fold(dstp->bits, origp->bits, sz, nr_cpumask_bits);
}

static inline void cpumask_copy(struct cpumask *dstp,
const struct cpumask *srcp)
{
- bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), NR_CPUS);
+ bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
}

/*
@@ -468,34 +456,22 @@ int __any_online_cpu(const cpumask_t *ma
#define for_each_cpu_mask(cpu, mask) \
for ((cpu) = -1; \
(cpu) = next_cpu((cpu), (mask)), \
- (cpu) < NR_CPUS;)
+ (cpu) < nr_cpu_ids;)
#define for_each_cpu_mask_and(cpu, mask, and) \
for ((cpu) = -1; \
(cpu) = cpumask_next_and((cpu), &(mask), &(and)), \
(cpu) < nr_cpu_ids;)
-#endif

-#define cpumask_first_and(mask, and) cpumask_next_and(-1, (mask), (and))
-
-#if NR_CPUS <= 64
-
-#define next_cpu_nr(n, src) next_cpu(n, src)
-#define cpus_weight_nr(cpumask) cpus_weight(cpumask)
-#define for_each_cpu_mask_nr(cpu, mask) for_each_cpu_mask(cpu, mask)
-
-#else /* NR_CPUS > 64 */
-
-int __next_cpu_nr(int n, const cpumask_t *srcp);
-
-#define next_cpu_nr(n, src) __next_cpu_nr((n), &(src))
-#define cpus_weight_nr(cpumask) __cpus_weight(&(cpumask), nr_cpu_ids)
-
-#define for_each_cpu_mask_nr(cpu, mask) \
- for ((cpu) = -1; \
- (cpu) = next_cpu_nr((cpu), (mask)), \
- (cpu) < nr_cpu_ids;)
+#define num_online_cpus() cpus_weight(cpu_online_map)
+#define num_possible_cpus() cpus_weight(cpu_possible_map)
+#define num_present_cpus() cpus_weight(cpu_present_map)
+#define cpu_online(cpu) cpu_isset((cpu), cpu_online_map)
+#define cpu_possible(cpu) cpu_isset((cpu), cpu_possible_map)
+#define cpu_present(cpu) cpu_isset((cpu), cpu_present_map)
+#define cpu_active(cpu) cpu_isset((cpu), cpu_active_map)
+#endif /* NR_CPUS */

-#endif /* NR_CPUS > 64 */
+#define cpumask_first_and(mask, and) cpumask_next_and(-1, (mask), (and))

/*
* cpumask_var_t: struct cpumask for stack usage.
@@ -596,9 +572,9 @@ extern cpumask_t cpu_present_map;
extern cpumask_t cpu_active_map;

#if NR_CPUS > 1
-#define num_online_cpus() cpus_weight_nr(cpu_online_map)
-#define num_possible_cpus() cpus_weight_nr(cpu_possible_map)
-#define num_present_cpus() cpus_weight_nr(cpu_present_map)
+#define num_online_cpus() cpus_weight(cpu_online_map)
+#define num_possible_cpus() cpus_weight(cpu_possible_map)
+#define num_present_cpus() cpus_weight(cpu_present_map)
#define cpu_online(cpu) cpu_isset((cpu), cpu_online_map)
#define cpu_possible(cpu) cpu_isset((cpu), cpu_possible_map)
#define cpu_present(cpu) cpu_isset((cpu), cpu_present_map)
@@ -615,8 +591,8 @@ extern cpumask_t cpu_active_map;

#define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))

-#define for_each_possible_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_possible_map)
-#define for_each_online_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_online_map)
-#define for_each_present_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_present_map)
+#define for_each_possible_cpu(cpu) for_each_cpu_mask((cpu), cpu_possible_map)
+#define for_each_online_cpu(cpu) for_each_cpu_mask((cpu), cpu_online_map)
+#define for_each_present_cpu(cpu) for_each_cpu_mask((cpu), cpu_present_map)

#endif /* __LINUX_CPUMASK_H */
--- linux-2.6.28.orig/include/linux/seq_file.h
+++ linux-2.6.28/include/linux/seq_file.h
@@ -52,7 +52,7 @@ int seq_path_root(struct seq_file *m, st
int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits);
static inline int seq_cpumask(struct seq_file *m, cpumask_t *mask)
{
- return seq_bitmap(m, mask->bits, NR_CPUS);
+ return seq_bitmap(m, mask->bits, nr_cpu_ids);
}

static inline int seq_nodemask(struct seq_file *m, nodemask_t *mask)
--- linux-2.6.28.orig/lib/cpumask.c
+++ linux-2.6.28/lib/cpumask.c
@@ -5,33 +5,25 @@

int __first_cpu(const cpumask_t *srcp)
{
- return find_first_bit(srcp->bits, NR_CPUS);
+ return find_first_bit(srcp->bits, nr_cpumask_bits);
}
EXPORT_SYMBOL(__first_cpu);

int __next_cpu(int n, const cpumask_t *srcp)
{
- return find_next_bit(srcp->bits, NR_CPUS, n+1);
+ return find_next_bit(srcp->bits, nr_cpumask_bits, n+1);
}
EXPORT_SYMBOL(__next_cpu);

int cpumask_next_and(int n, const cpumask_t *srcp, const cpumask_t *andp)
{
- while ((n = next_cpu_nr(n, *srcp)) < nr_cpu_ids)
+ while ((n = next_cpu(n, *srcp)) < nr_cpu_ids)
if (cpumask_test_cpu(n, andp))
break;
return n;
}
EXPORT_SYMBOL(cpumask_next_and);

-#if NR_CPUS > 64
-int __next_cpu_nr(int n, const cpumask_t *srcp)
-{
- return find_next_bit(srcp->bits, nr_cpu_ids, n+1);
-}
-EXPORT_SYMBOL(__next_cpu_nr);
-#endif
-
int __any_online_cpu(const cpumask_t *mask)
{
int cpu;
--


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