The for_each_cpu_mask loop is used quite often in the kernel. It
makes use of two functions: first_cpu and next_cpu. This patch
changes for_each_cpu_mask to use only one function: a newly
introduced find_next_cpu. Each use of the for_each_cpu_mask
constuct then becomes a few bytes smaller. An x86_64 defconfig
kernel is about 2000 bytes smaller with this patch applied:
text data bss dec hex filename
5395732 976736 734280 7106748 6c70bc vmlinux.orig
5393639 976736 734280 7104655 6c688f vmlinux
Runs fine on qemu UP/SMP x86_64/i386.
Signed-off-by: Alexander van Heukelum <heukelum@xxxxxxxxxxx>
---
Hello Andrew,
Could you add this patch to -mm?
Greetings,
Alexander
include/linux/cpumask.h | 14 ++++++++------
lib/cpumask.c | 6 ++++++
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 9650806..a760e29 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -221,9 +221,11 @@ int __first_cpu(const cpumask_t *srcp);
#define first_cpu(src) __first_cpu(&(src))
int __next_cpu(int n, const cpumask_t *srcp);
#define next_cpu(n, src) __next_cpu((n), &(src))
+int find_next_cpu_mask(int n, const cpumask_t *srcp);
#else
-#define first_cpu(src) ({ (void)(src); 0; })
-#define next_cpu(n, src) ({ (void)(src); 1; })
+#define first_cpu(src) ({ (void)(src); 0; })
+#define next_cpu(n, src) ({ (void)(src); 1; })
+#define find_next_cpu_mask(n, src) ({ (void)(src); n; })
#endif
#ifdef CONFIG_HAVE_CPUMASK_OF_CPU_MAP
@@ -351,10 +353,10 @@ static inline void __cpus_fold(cpumask_t *dstp, const cpumask_t *origp,
}
#if NR_CPUS > 1
-#define for_each_cpu_mask(cpu, mask) \
- for ((cpu) = first_cpu(mask); \
- (cpu) < NR_CPUS; \
- (cpu) = next_cpu((cpu), (mask)))
+#define for_each_cpu_mask(cpu, mask) \
+ for ((cpu) = 0; \
+ (cpu) = find_next_cpu_mask((cpu), &(mask)), \
+ (cpu) < NR_CPUS; (cpu)++)
#else /* NR_CPUS == 1 */
#define for_each_cpu_mask(cpu, mask) \
for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
diff --git a/lib/cpumask.c b/lib/cpumask.c
index bb4f76d..93dd6ca 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -15,6 +15,12 @@ int __next_cpu(int n, const cpumask_t *srcp)
}
EXPORT_SYMBOL(__next_cpu);
+int find_next_cpu_mask(int n, const cpumask_t *srcp)
+{
+ return find_next_bit(srcp->bits, NR_CPUS, n);
+}
+EXPORT_SYMBOL(find_next_cpu_mask);
+
int __any_online_cpu(const cpumask_t *mask)
{
int cpu;
--
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