[PATCH 11/14] pktgen: spin using hrtimer
From: Stephen Hemminger <hidden>
Date: 2009-08-27 23:59:19
This changes how the pktgen thread spins/waits between packets if delay is configured. It uses a high res timer to wait for time to arrive. Signed-off-by: Stephen Hemminger <redacted> --- kernel/hrtimer.c | 1 + net/core/pktgen.c | 49 ++++++++++++++++++++++++++++--------------------- 2 files changed, 29 insertions(+), 21 deletions(-)
--- a/net/core/pktgen.c 2009-08-27 16:00:52.538250235 -0700
+++ b/net/core/pktgen.c 2009-08-27 16:28:17.520270294 -0700@@ -131,6 +131,7 @@ #include <linux/ioport.h> #include <linux/interrupt.h> #include <linux/capability.h> +#include <linux/hrtimer.h> #include <linux/freezer.h> #include <linux/delay.h> #include <linux/timer.h>
@@ -2086,33 +2087,40 @@ static void pktgen_setup_inject(struct p pkt_dev->nflows = 0; } -static inline s64 delta_ns(ktime_t a, ktime_t b) -{ - return ktime_to_ns(ktime_sub(a, b)); -} static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) { - ktime_t start, now; - s64 dt; + ktime_t start; + s32 remaining; + struct hrtimer_sleeper t; - start = now = ktime_now(); + hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + hrtimer_set_expires(&t.timer, spin_until); - while ((dt = delta_ns(spin_until, now)) > 0) { - /* TODO: optimize sleeping behavior */ - if (dt > TICK_NSEC) - schedule_timeout_interruptible(1); - else if (dt > 100*NSEC_PER_USEC) { - if (!pkt_dev->running) - return; - if (need_resched()) + remaining = ktime_to_us(hrtimer_expires_remaining(&t.timer)); + if (remaining <= 0) + return; + + start = ktime_now(); + if (remaining < 100) + udelay(remaining); /* really small just spin */ + else { + /* see do_nanosleep */ + hrtimer_init_sleeper(&t, current); + do { + set_current_state(TASK_INTERRUPTIBLE); + hrtimer_start_expires(&t.timer, HRTIMER_MODE_ABS); + if (!hrtimer_active(&t.timer)) + t.task = NULL; + + if (likely(t.task)) schedule(); - } - now = ktime_now(); + hrtimer_cancel(&t.timer); + } while (t.task && pkt_dev->running && !signal_pending(current)); + __set_current_state(TASK_RUNNING); } - - pkt_dev->idle_acc += ktime_to_ns(ktime_sub(now, start)); + pkt_dev->idle_acc += ktime_to_ns(ktime_sub(ktime_now(), start)); } static inline void set_pkt_overhead(struct pktgen_dev *pkt_dev)
@@ -3360,8 +3368,7 @@ static void pktgen_xmit(struct pktgen_de int ret; if (pkt_dev->delay) { - if (ktime_lt(ktime_now(), pkt_dev->next_tx)) - spin(pkt_dev, pkt_dev->next_tx); + spin(pkt_dev, pkt_dev->next_tx); /* This is max DELAY, this has special meaning of * "never transmit" --- a/kernel/hrtimer.c 2009-08-27 16:00:52.547269763 -0700 +++ b/kernel/hrtimer.c 2009-08-27 16:02:04.543287103 -0700
@@ -1477,6 +1477,7 @@ void hrtimer_init_sleeper(struct hrtimer sl->timer.function = hrtimer_wakeup; sl->task = task; } +EXPORT_SYMBOL_GPL(hrtimer_init_sleeper); static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode) {
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