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authorAnna-Maria Gleixner <anna-maria@linutronix.de>2017-12-21 11:41:57 +0100
committerIngo Molnar <mingo@kernel.org>2018-01-16 09:51:22 +0100
commit5da70160462e80b0ab8a6960cdd0cdd476907523 (patch)
tree5c180b5cfd65a2fae7b4e53f374f9e0747cb349f /include/linux/hrtimer.h
parentc458b1d102036eaa2c70e03000c959bd491c2037 (diff)
hrtimer: Implement support for softirq based hrtimers
hrtimer callbacks are always invoked in hard interrupt context. Several users in tree require soft interrupt context for their callbacks and achieve this by combining a hrtimer with a tasklet. The hrtimer schedules the tasklet in hard interrupt context and the tasklet callback gets invoked in softirq context later. That's suboptimal and aside of that the real-time patch moves most of the hrtimers into softirq context. So adding native support for hrtimers expiring in softirq context is a valuable extension for both mainline and the RT patch set. Each valid hrtimer clock id has two associated hrtimer clock bases: one for timers expiring in hardirq context and one for timers expiring in softirq context. Implement the functionality to associate a hrtimer with the hard or softirq related clock bases and update the relevant functions to take them into account when the next expiry time needs to be evaluated. Add a check into the hard interrupt context handler functions to check whether the first expiring softirq based timer has expired. If it's expired the softirq is raised and the accounting of softirq based timers to evaluate the next expiry time for programming the timer hardware is skipped until the softirq processing has finished. At the end of the softirq processing the regular processing is resumed. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Christoph Hellwig <hch@lst.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: keescook@chromium.org Link: http://lkml.kernel.org/r/20171221104205.7269-29-anna-maria@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/hrtimer.h')
-rw-r--r--include/linux/hrtimer.h21
1 files changed, 16 insertions, 5 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 26ae8a868ea8..c7902ca7c9f4 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -103,6 +103,7 @@ enum hrtimer_restart {
* @base: pointer to the timer base (per cpu and per clock)
* @state: state information (See bit values above)
* @is_rel: Set if the timer was armed relative
+ * @is_soft: Set if hrtimer will be expired in soft interrupt context.
*
* The hrtimer structure must be initialized by hrtimer_init()
*/
@@ -113,6 +114,7 @@ struct hrtimer {
struct hrtimer_clock_base *base;
u8 state;
u8 is_rel;
+ u8 is_soft;
};
/**
@@ -178,13 +180,18 @@ enum hrtimer_base_type {
* @hres_active: State of high resolution mode
* @in_hrtirq: hrtimer_interrupt() is currently executing
* @hang_detected: The last hrtimer interrupt detected a hang
+ * @softirq_activated: displays, if the softirq is raised - update of softirq
+ * related settings is not required then.
* @nr_events: Total number of hrtimer interrupt events
* @nr_retries: Total number of hrtimer interrupt retries
* @nr_hangs: Total number of hrtimer interrupt hangs
* @max_hang_time: Maximum time spent in hrtimer_interrupt
* @expires_next: absolute time of the next event, is required for remote
- * hrtimer enqueue
+ * hrtimer enqueue; it is the total first expiry time (hard
+ * and soft hrtimer are taken into account)
* @next_timer: Pointer to the first expiring timer
+ * @softirq_expires_next: Time to check, if soft queues needs also to be expired
+ * @softirq_next_timer: Pointer to the first expiring softirq based timer
* @clock_base: array of clock bases for this cpu
*
* Note: next_timer is just an optimization for __remove_hrtimer().
@@ -196,9 +203,10 @@ struct hrtimer_cpu_base {
unsigned int cpu;
unsigned int active_bases;
unsigned int clock_was_set_seq;
- unsigned int hres_active : 1,
- in_hrtirq : 1,
- hang_detected : 1;
+ unsigned int hres_active : 1,
+ in_hrtirq : 1,
+ hang_detected : 1,
+ softirq_activated : 1;
#ifdef CONFIG_HIGH_RES_TIMERS
unsigned int nr_events;
unsigned short nr_retries;
@@ -207,6 +215,8 @@ struct hrtimer_cpu_base {
#endif
ktime_t expires_next;
struct hrtimer *next_timer;
+ ktime_t softirq_expires_next;
+ struct hrtimer *softirq_next_timer;
struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
} ____cacheline_aligned;
@@ -379,7 +389,8 @@ extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
* @timer: the timer to be added
* @tim: expiry time
* @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
- * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
+ * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
+ * softirq based mode is considered for debug purpose only!
*/
static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
const enum hrtimer_mode mode)