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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2017-09-08 16:14:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-08 18:26:48 -0700 |
| commit | 9b130ad5bb8255ee8534d92d67e12b2a4887eacb (patch) | |
| tree | 125a5e867be6b0dbd4958ca41426e2c733768110 /kernel/smp.c | |
| parent | ac036f9570a2d318b7d8dbbdbf0e269d7cc68cef (diff) | |
| download | linux-9b130ad5bb8255ee8534d92d67e12b2a4887eacb.tar.gz | |
treewide: make "nr_cpu_ids" unsigned
First, number of CPUs can't be negative number. Second, different signnnedness leads to suboptimal code in the following cases: 1) kmalloc(nr_cpu_ids * sizeof(X)); "int" has to be sign extended to size_t. 2) while (loff_t *pos < nr_cpu_ids) MOVSXD is 1 byte longed than the same MOV. Other cases exist as well. Basically compiler is told that nr_cpu_ids can't be negative which can't be deduced if it is "int". Code savings on allyesconfig kernel: -3KB add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370) function old new delta coretemp_cpu_online 450 512 +62 rcu_init_one 1234 1272 +38 pci_device_probe 374 399 +25 ... pgdat_reclaimable_pages 628 556 -72 select_fallback_rq 446 369 -77 task_numa_find_cpu 1923 1807 -116 Link: http://lkml.kernel.org/r/20170819114959.GA30580@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 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 81cfca9b4cc3..c94dd85c8d41 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -550,7 +550,7 @@ static int __init maxcpus(char *str) early_param("maxcpus", maxcpus); /* Setup number of possible processor ids */ -int nr_cpu_ids __read_mostly = NR_CPUS; +unsigned int nr_cpu_ids __read_mostly = NR_CPUS; EXPORT_SYMBOL(nr_cpu_ids); /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ |