From: Nathan Lynch <ntl@pobox.com>
The rtasd thread should not hold the cpucontrol semaphore while sleeping
between event scans in its first pass; it needlessly delays boot by one
second per cpu when CONFIG_HOTPLUG_CPU=y.
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/ppc64/kernel/rtasd.c | 61 ++++++++++++++++++--------------------
1 files changed, 30 insertions(+), 31 deletions(-)
diff -puN arch/ppc64/kernel/rtasd.c~ppc64-rtasd-shouldnt-hold-cpucontrol-while-sleeping arch/ppc64/kernel/rtasd.c
--- 25/arch/ppc64/kernel/rtasd.c~ppc64-rtasd-shouldnt-hold-cpucontrol-while-sleeping 2005-03-16 00:37:26.000000000 -0800
+++ 25-akpm/arch/ppc64/kernel/rtasd.c 2005-03-16 00:37:26.000000000 -0800
@@ -399,10 +399,33 @@ static void do_event_scan(int event_scan
} while(error == 0);
}
+static void do_event_scan_all_cpus(long delay)
+{
+ int cpu;
+
+ lock_cpu_hotplug();
+ cpu = first_cpu(cpu_online_map);
+ for (;;) {
+ set_cpus_allowed(current, cpumask_of_cpu(cpu));
+ do_event_scan(rtas_token("event-scan"));
+ set_cpus_allowed(current, CPU_MASK_ALL);
+
+ /* Drop hotplug lock, and sleep for the specified delay */
+ unlock_cpu_hotplug();
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(delay);
+ lock_cpu_hotplug();
+
+ cpu = next_cpu(cpu, cpu_online_map);
+ if (cpu == NR_CPUS)
+ break;
+ }
+ unlock_cpu_hotplug();
+}
+
static int rtasd(void *unused)
{
unsigned int err_type;
- int cpu = 0;
int event_scan = rtas_token("event-scan");
int rc;
@@ -436,17 +459,7 @@ static int rtasd(void *unused)
}
/* First pass. */
- lock_cpu_hotplug();
- for_each_online_cpu(cpu) {
- DEBUG("scheduling on %d\n", cpu);
- set_cpus_allowed(current, cpumask_of_cpu(cpu));
- DEBUG("watchdog scheduled on cpu %d\n", smp_processor_id());
-
- do_event_scan(event_scan);
- set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout(HZ);
- }
- unlock_cpu_hotplug();
+ do_event_scan_all_cpus(HZ);
if (surveillance_timeout != -1) {
DEBUG("enabling surveillance\n");
@@ -454,25 +467,11 @@ static int rtasd(void *unused)
DEBUG("surveillance enabled\n");
}
- lock_cpu_hotplug();
- cpu = first_cpu(cpu_online_map);
- for (;;) {
- set_cpus_allowed(current, cpumask_of_cpu(cpu));
- do_event_scan(event_scan);
- set_cpus_allowed(current, CPU_MASK_ALL);
-
- /* Drop hotplug lock, and sleep for a bit (at least
- * one second since some machines have problems if we
- * call event-scan too quickly). */
- unlock_cpu_hotplug();
- set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout((HZ*60/rtas_event_scan_rate) / 2);
- lock_cpu_hotplug();
-
- cpu = next_cpu(cpu, cpu_online_map);
- if (cpu == NR_CPUS)
- cpu = first_cpu(cpu_online_map);
- }
+ /* Delay should be at least one second since some
+ * machines have problems if we call event-scan too
+ * quickly. */
+ for (;;)
+ do_event_scan_all_cpus((HZ*60/rtas_event_scan_rate) / 2);
error:
/* Should delete proc entries */
_