[S390] ap: Use high-resolution timer for polling
The ap poll mechanism is converted to use a high-resolution timer for
polling. This allows more specific polling. With this a new sysfs
attribute is introduced to specify the polling rate in nanoseconds.
Signed-off-by: Felix Beck <felix.beck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index a1ab3e3..62b6b55 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -34,13 +34,15 @@
#include <linux/mutex.h>
#include <asm/s390_rdev.h>
#include <asm/reset.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
#include "ap_bus.h"
/* Some prototypes. */
static void ap_scan_bus(struct work_struct *);
static void ap_poll_all(unsigned long);
-static void ap_poll_timeout(unsigned long);
+static enum hrtimer_restart ap_poll_timeout(struct hrtimer *);
static int ap_poll_thread_start(void);
static void ap_poll_thread_stop(void);
static void ap_request_timeout(unsigned long);
@@ -80,12 +82,15 @@
/*
* Tasklet & timer for AP request polling.
*/
-static struct timer_list ap_poll_timer = TIMER_INITIALIZER(ap_poll_timeout,0,0);
static DECLARE_TASKLET(ap_tasklet, ap_poll_all, 0);
static atomic_t ap_poll_requests = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
static struct task_struct *ap_poll_kthread = NULL;
static DEFINE_MUTEX(ap_poll_thread_mutex);
+static struct hrtimer ap_poll_timer;
+/* In LPAR poll with 4kHz frequency. Poll every 250000 nanoseconds.
+ * If z/VM change to 1500000 nanoseconds to adjust to z/VM polling.*/
+static unsigned long long poll_timeout = 250000;
/**
* ap_intructions_available() - Test if AP instructions are available.
@@ -636,11 +641,39 @@
static BUS_ATTR(poll_thread, 0644, ap_poll_thread_show, ap_poll_thread_store);
+static ssize_t poll_timeout_show(struct bus_type *bus, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%llu\n", poll_timeout);
+}
+
+static ssize_t poll_timeout_store(struct bus_type *bus, const char *buf,
+ size_t count)
+{
+ unsigned long long time;
+ ktime_t hr_time;
+
+ /* 120 seconds = maximum poll interval */
+ if (sscanf(buf, "%llu\n", &time) != 1 || time < 1 || time > 120000000000)
+ return -EINVAL;
+ poll_timeout = time;
+ hr_time = ktime_set(0, poll_timeout);
+
+ if (!hrtimer_is_queued(&ap_poll_timer) ||
+ !hrtimer_forward(&ap_poll_timer, ap_poll_timer.expires, hr_time)) {
+ ap_poll_timer.expires = hr_time;
+ hrtimer_start(&ap_poll_timer, hr_time, HRTIMER_MODE_ABS);
+ }
+ return count;
+}
+
+static BUS_ATTR(poll_timeout, 0644, poll_timeout_show, poll_timeout_store);
+
static struct bus_attribute *const ap_bus_attrs[] = {
&bus_attr_ap_domain,
&bus_attr_config_time,
&bus_attr_poll_thread,
- NULL
+ &bus_attr_poll_timeout,
+ NULL,
};
/**
@@ -895,9 +928,10 @@
*/
static inline void ap_schedule_poll_timer(void)
{
- if (timer_pending(&ap_poll_timer))
+ if (hrtimer_is_queued(&ap_poll_timer))
return;
- mod_timer(&ap_poll_timer, jiffies + AP_POLL_TIME);
+ hrtimer_start(&ap_poll_timer, ktime_set(0, poll_timeout),
+ HRTIMER_MODE_ABS);
}
/**
@@ -1115,13 +1149,14 @@
/**
* ap_poll_timeout(): AP receive polling for finished AP requests.
- * @unused: Unused variable.
+ * @unused: Unused pointer.
*
- * Schedules the AP tasklet.
+ * Schedules the AP tasklet using a high resolution timer.
*/
-static void ap_poll_timeout(unsigned long unused)
+static enum hrtimer_restart ap_poll_timeout(struct hrtimer *unused)
{
tasklet_schedule(&ap_tasklet);
+ return HRTIMER_NORESTART;
}
/**
@@ -1344,6 +1379,14 @@
ap_config_timer.expires = jiffies + ap_config_time * HZ;
add_timer(&ap_config_timer);
+ /* Setup the high resultion poll timer.
+ * If we are running under z/VM adjust polling to z/VM polling rate.
+ */
+ if (MACHINE_IS_VM)
+ poll_timeout = 1500000;
+ hrtimer_init(&ap_poll_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+ ap_poll_timer.function = ap_poll_timeout;
+
/* Start the low priority AP bus poll thread. */
if (ap_thread_flag) {
rc = ap_poll_thread_start();
@@ -1355,7 +1398,7 @@
out_work:
del_timer_sync(&ap_config_timer);
- del_timer_sync(&ap_poll_timer);
+ hrtimer_cancel(&ap_poll_timer);
destroy_workqueue(ap_work_queue);
out_root:
s390_root_dev_unregister(ap_root_device);
@@ -1386,7 +1429,7 @@
ap_reset_domain();
ap_poll_thread_stop();
del_timer_sync(&ap_config_timer);
- del_timer_sync(&ap_poll_timer);
+ hrtimer_cancel(&ap_poll_timer);
destroy_workqueue(ap_work_queue);
tasklet_kill(&ap_tasklet);
s390_root_dev_unregister(ap_root_device);