From 9b130ad5bb8255ee8534d92d67e12b2a4887eacb Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Sep 2017 16:14:18 -0700 Subject: 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/smp.c') 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 */ -- cgit v1.2.3-58-ga151