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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2017-09-08 16:17:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-08 18:26:51 -0700 |
| commit | f22ef333c32cc683922d7e3361a83ebc31b2ac6d (patch) | |
| tree | 57173374d87f88a280e80a6b7b8ee3eb237d2c0b /lib | |
| parent | 0ce2c2029312ed78e37b56b08fa0f59ba97ef50b (diff) | |
| download | lwn-f22ef333c32cc683922d7e3361a83ebc31b2ac6d.tar.gz lwn-f22ef333c32cc683922d7e3361a83ebc31b2ac6d.zip | |
cpumask: make cpumask_next() out-of-line
Every for_each_XXX_cpu() invocation calls cpumask_next() which is an
inline function:
static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
{
/* -1 is a legal arg here. */
if (n != -1)
cpumask_check(n);
return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
}
However!
find_next_bit() is regular out-of-line function which means "nr_cpu_ids"
load and increment happen at the caller resulting in a lot of bloat
x86_64 defconfig:
add/remove: 3/0 grow/shrink: 8/373 up/down: 155/-5668 (-5513)
x86_64 allyesconfig-ish:
add/remove: 3/1 grow/shrink: 57/634 up/down: 3515/-28177 (-24662) !!!
Some archs redefine find_next_bit() but it is OK:
m68k inline but SMP is not supported
arm out-of-line
unicore32 out-of-line
Function call will happen anyway, so move load and increment into callee.
Link: http://lkml.kernel.org/r/20170824230010.GA1593@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/cpumask.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/lib/cpumask.c b/lib/cpumask.c index 4731a0895760..8b1a1bd77539 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -6,6 +6,22 @@ #include <linux/bootmem.h> /** + * cpumask_next - get the next cpu in a cpumask + * @n: the cpu prior to the place to search (ie. return will be > @n) + * @srcp: the cpumask pointer + * + * Returns >= nr_cpu_ids if no further cpus set. + */ +unsigned int cpumask_next(int n, const struct cpumask *srcp) +{ + /* -1 is a legal arg here. */ + if (n != -1) + cpumask_check(n); + return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1); +} +EXPORT_SYMBOL(cpumask_next); + +/** * cpumask_next_and - get the next cpu in *src1p & *src2p * @n: the cpu prior to the place to search (ie. return will be > @n) * @src1p: the first cpumask pointer |