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authorThomas Gleixner <tglx@linutronix.de>2019-08-27 21:31:02 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-08-28 11:50:43 +0200
commit60bda037f1dd8151e0c9ee5b09f0c091a0f643cd (patch)
treeac8ed446c0ae7fcdf72285d5ca99531a3f96560b /include/linux/posix-timers.h
parent244d49e30653658d4e7e9b2b8427777cbbc5affe (diff)
posix-cpu-timers: Utilize timerqueue for storage
Using a linear O(N) search for timer insertion affects execution time and D-cache footprint badly with a larger number of timers. Switch the storage to a timerqueue which is already used for hrtimers and alarmtimers. It does not affect the size of struct k_itimer as it.alarm is still larger. The extra list head for the expiry list will go away later once the expiry is moved into task work context. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908272129220.1939@nanos.tec.linutronix.de
Diffstat (limited to 'include/linux/posix-timers.h')
-rw-r--r--include/linux/posix-timers.h65
1 files changed, 49 insertions, 16 deletions
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index a9e3f69d2db4..f9fbb4c620c1 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -5,17 +5,11 @@
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/alarmtimer.h>
+#include <linux/timerqueue.h>
struct kernel_siginfo;
struct task_struct;
-struct cpu_timer_list {
- struct list_head entry;
- u64 expires;
- struct task_struct *task;
- int firing;
-};
-
/*
* Bit fields within a clockid:
*
@@ -65,13 +59,57 @@ static inline int clockid_to_fd(const clockid_t clk)
#ifdef CONFIG_POSIX_TIMERS
/**
+ * cpu_timer - Posix CPU timer representation for k_itimer
+ * @node: timerqueue node to queue in the task/sig
+ * @head: timerqueue head on which this timer is queued
+ * @task: Pointer to target task
+ * @elist: List head for the expiry list
+ * @firing: Timer is currently firing
+ */
+struct cpu_timer {
+ struct timerqueue_node node;
+ struct timerqueue_head *head;
+ struct task_struct *task;
+ struct list_head elist;
+ int firing;
+};
+
+static inline bool cpu_timer_requeue(struct cpu_timer *ctmr)
+{
+ return timerqueue_add(ctmr->head, &ctmr->node);
+}
+
+static inline bool cpu_timer_enqueue(struct timerqueue_head *head,
+ struct cpu_timer *ctmr)
+{
+ ctmr->head = head;
+ return timerqueue_add(head, &ctmr->node);
+}
+
+static inline void cpu_timer_dequeue(struct cpu_timer *ctmr)
+{
+ if (!RB_EMPTY_NODE(&ctmr->node.node))
+ timerqueue_del(ctmr->head, &ctmr->node);
+}
+
+static inline u64 cpu_timer_getexpires(struct cpu_timer *ctmr)
+{
+ return ctmr->node.expires;
+}
+
+static inline void cpu_timer_setexpires(struct cpu_timer *ctmr, u64 exp)
+{
+ ctmr->node.expires = exp;
+}
+
+/**
* posix_cputimer_base - Container per posix CPU clock
* @nextevt: Earliest-expiration cache
- * @cpu_timers: List heads to queue posix CPU timers
+ * @tqhead: timerqueue head for cpu_timers
*/
struct posix_cputimer_base {
u64 nextevt;
- struct list_head cpu_timers;
+ struct timerqueue_head tqhead;
};
/**
@@ -92,14 +130,10 @@ struct posix_cputimers {
static inline void posix_cputimers_init(struct posix_cputimers *pct)
{
- pct->timers_active = 0;
- pct->expiry_active = 0;
+ memset(pct, 0, sizeof(*pct));
pct->bases[0].nextevt = U64_MAX;
pct->bases[1].nextevt = U64_MAX;
pct->bases[2].nextevt = U64_MAX;
- INIT_LIST_HEAD(&pct->bases[0].cpu_timers);
- INIT_LIST_HEAD(&pct->bases[1].cpu_timers);
- INIT_LIST_HEAD(&pct->bases[2].cpu_timers);
}
void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit);
@@ -113,7 +147,6 @@ static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct,
/* Init task static initializer */
#define INIT_CPU_TIMERBASE(b) { \
.nextevt = U64_MAX, \
- .cpu_timers = LIST_HEAD_INIT(b.cpu_timers), \
}
#define INIT_CPU_TIMERBASES(b) { \
@@ -182,7 +215,7 @@ struct k_itimer {
struct {
struct hrtimer timer;
} real;
- struct cpu_timer_list cpu;
+ struct cpu_timer cpu;
struct {
struct alarm alarmtimer;
} alarm;