From: Henrik Austad <[email protected]> This allows userspace to set the forced CPU via sysfs in /sys/kernel/timekeeping/forced_cpu.
CC: Thomas Gleixner <[email protected]> CC: Peter Zijlstra <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: John Stultz <[email protected]> CC: Paul E. McKenney <[email protected]> Signed-off-by: Henrik Austad <[email protected]> --- kernel/time/timekeeping.c | 36 ++++++++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 4bdfa11..b148062 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -44,23 +44,47 @@ int expose_tick_forced_timer_cpu = -1; /* * sysfs interface to timer-cpu */ -static ssize_t current_cpu_show(struct kobject *kobj, - struct kobj_attribute *attr, - char *buf) -{ - return sprintf(buf, "%d\n", tick_expose_cpu()); +static ssize_t cpu_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + int var = -EINVAL; + if (strcmp(attr->attr.name, "current_cpu") == 0) + var = sprintf(buf, "%d\n", tick_expose_cpu()); + else if (strcmp(attr->attr.name, "forced_cpu") == 0) + var = sprintf(buf, "%d\n", tick_get_forced_cpu()); + return var; +} + +static ssize_t cpu_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char * buf, + size_t count) +{ + int var = 0; + if (strcmp(attr->attr.name, "forced_cpu") == 0) { + sscanf(buf, "%du", &var); + if ((var = tick_set_forced_cpu(var)) != 0) { + pr_err("trouble setting forced CPU (%d)\n", var); + } + } + return count; } static struct kobj_attribute current_cpu_attribute = - __ATTR_RO(current_cpu); + __ATTR(current_cpu, 0444, cpu_show, NULL); +static struct kobj_attribute forced_cpu_attribute = + __ATTR(forced_cpu, 0644, cpu_show, cpu_store); static struct attribute *timekeeping_attrs[] = { ¤t_cpu_attribute.attr, + &forced_cpu_attribute.attr, NULL, }; static struct attribute_group timekeeping_ag = { .attrs = timekeeping_attrs, }; + static struct kobject *timekeeping_kobj; static __init int timekeeping_sysfs_init(void) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
