[S390] topology: increase poll frequency if change is anticipated
Increase cpu topology change poll frequency if a change is anticipated.
Otherwise a user might be a bit confused to have to wait up to a minute
in order to see a change this should be visible immediatly.
However there is no guarantee that the change will happen during the
time frame the poll frequency is increased.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index 7016dd7..0837de8 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h
@@ -35,11 +35,13 @@
int topology_set_cpu_management(int fc);
void topology_schedule_update(void);
void store_topology(struct sysinfo_15_1_x *info);
+void topology_expect_change(void);
#else /* CONFIG_SCHED_BOOK */
static inline void topology_schedule_update(void) { }
static inline int topology_cpu_init(struct cpu *cpu) { return 0; }
+static inline void topology_expect_change(void) { }
#endif /* CONFIG_SCHED_BOOK */
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 109e742..8aba77d 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -867,6 +867,7 @@
if (!rc) {
smp_cpu_state[cpu] = CPU_STATE_STANDBY;
cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
+ topology_expect_change();
}
}
break;
@@ -876,6 +877,7 @@
if (!rc) {
smp_cpu_state[cpu] = CPU_STATE_CONFIGURED;
cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
+ topology_expect_change();
}
}
break;
diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index 2abad30..e06fb85 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -31,7 +31,6 @@
static int topology_enabled = 1;
static void topology_work_fn(struct work_struct *work);
static struct sysinfo_15_1_x *tl_info;
-static struct timer_list topology_timer;
static void set_topology_timer(void);
static DECLARE_WORK(topology_work, topology_work_fn);
/* topology_lock protects the core linked list */
@@ -297,12 +296,30 @@
set_topology_timer();
}
+static struct timer_list topology_timer =
+ TIMER_DEFERRED_INITIALIZER(topology_timer_fn, 0, 0);
+
+static atomic_t topology_poll = ATOMIC_INIT(0);
+
static void set_topology_timer(void)
{
- topology_timer.function = topology_timer_fn;
- topology_timer.data = 0;
- topology_timer.expires = jiffies + 60 * HZ;
- add_timer(&topology_timer);
+ if (atomic_add_unless(&topology_poll, -1, 0))
+ mod_timer(&topology_timer, jiffies + HZ / 10);
+ else
+ mod_timer(&topology_timer, jiffies + HZ * 60);
+}
+
+void topology_expect_change(void)
+{
+ if (!MACHINE_HAS_TOPOLOGY)
+ return;
+ /* This is racy, but it doesn't matter since it is just a heuristic.
+ * Worst case is that we poll in a higher frequency for a bit longer.
+ */
+ if (atomic_read(&topology_poll) > 60)
+ return;
+ atomic_add(60, &topology_poll);
+ set_topology_timer();
}
static int __init early_parse_topology(char *p)
@@ -379,8 +396,10 @@
if (cpu_management == val)
goto out;
rc = topology_set_cpu_management(val);
- if (!rc)
- cpu_management = val;
+ if (rc)
+ goto out;
+ cpu_management = val;
+ topology_expect_change();
out:
mutex_unlock(&smp_cpu_state_mutex);
put_online_cpus();
@@ -438,7 +457,6 @@
topology_update_polarization_simple();
goto out;
}
- init_timer_deferrable(&topology_timer);
set_topology_timer();
out:
update_cpu_core_map();