blktrace blkreplay: convert to use a dynamic cpu_set_t

Some distros have changed CPU_SETSIZE in glibc to 4096 since that matches
the NR_CPUS in the linux kernel config file.  Some distros have decided to
leave CPU_SETSIZE at 1024. This is a problem if you want to run that distro
on a very large machine.

CPU_SETSIZE is use by the struct cpu_set_t.  This means you to deal with cpus
greater the 1024 you must use the dynamic cpu sets, which involves converting
from things like CPU_SET to CPU_SET_S.

Cc: Jens Axboe <axboe@kernel.dk>

Modified by Jens to fix the CPU_{SET,ZERO}_S pointer mixup.

Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 11 insertions, 5 deletions

diff --git a/blktrace.c b/blktrace.c
index 63125ab..7e64c94 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -621,13 +621,19 @@ static void dpp_free(struct devpath *dpp)
 
 static int lock_on_cpu(int cpu)
 {
-	cpu_set_t cpu_mask;
-
-	CPU_ZERO(&cpu_mask);
-	CPU_SET(cpu, &cpu_mask);
-	if (sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask) < 0)
+	cpu_set_t * cpu_mask;
+	size_t size;
+	cpu_mask = CPU_ALLOC(ncpus);
+	size = CPU_ALLOC_SIZE(ncpus);
+
+	CPU_ZERO_S(size, cpu_mask);
+	CPU_SET_S(cpu, size, cpu_mask);
+	if (sched_setaffinity(0, size, cpu_mask) < 0) {
+		CPU_FREE(cpu_mask);		
 		return errno;
+	}
 
+	CPU_FREE(cpu_mask);		
 	return 0;
 }