I just noticed that I missed an include on submission here will,
resubmit v2 of patch 10 shortly.
A.
On 29/08/14 08:05, anton.iva...@kot-begemot.co.uk wrote:
> From: Anton Ivanov <antiv...@cisco.com>
>
> This patch adds an extra timer source which has correct timing
> and uses an up-to-date OS API and.
>
> Results - correct kernel behaviour on timer related tasks.
>
> 1. Improvement in network performance (TCP state machines
> are now fed correct time).
> 2. Correct QoS and traffic shaping.
>
> This improvement does not (and cannot) fix UML userspace. Its
> timer/time related behaviour is heavily dependent on getting
> VTALRM pacing which is instantiated on a per userspace thread
> basis. This patch does not fix this!!! It sorts out only the
> kernel side - forwarding, qos, tcp, etc.
>
> Signed-off-by: Anton Ivanov <antiv...@cisco.com>
> ---
> arch/um/Makefile | 2 +-
> arch/um/include/asm/irq.h | 3 +-
> arch/um/include/shared/kern_util.h | 1 +
> arch/um/include/shared/os.h | 5 +
> arch/um/kernel/irq.c | 12 +++
> arch/um/kernel/process.c | 7 +-
> arch/um/kernel/time.c | 44 ++++++---
> arch/um/os-Linux/signal.c | 47 +++++++++-
> arch/um/os-Linux/skas/process.c | 24 ++---
> arch/um/os-Linux/time.c | 178
> ++++++++++++++++++++++++++++--------
> 10 files changed, 250 insertions(+), 73 deletions(-)
>
> diff --git a/arch/um/Makefile b/arch/um/Makefile
> index 133f7de..9864fb7 100644
> --- a/arch/um/Makefile
> +++ b/arch/um/Makefile
> @@ -121,7 +121,7 @@ export LDS_ELF_FORMAT := $(ELF_FORMAT)
> # The wrappers will select whether using "malloc" or the kernel allocator.
> LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc
>
> -LD_FLAGS_CMDLINE = $(foreach opt,$(LDFLAGS),-Wl,$(opt))
> +LD_FLAGS_CMDLINE = $(foreach opt,$(LDFLAGS),-Wl,$(opt)) -lrt
>
> # Used by link-vmlinux.sh which has special support for um link
> export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE)
> diff --git a/arch/um/include/asm/irq.h b/arch/um/include/asm/irq.h
> index be9128b..4dd2f07 100644
> --- a/arch/um/include/asm/irq.h
> +++ b/arch/um/include/asm/irq.h
> @@ -22,8 +22,9 @@
> #define TELNETD_IRQ UM_END_ETH_IRQ + 7
> #define XTERM_IRQ UM_END_ETH_IRQ + 8
> #define RANDOM_IRQ UM_END_ETH_IRQ + 9
> +#define HRTIMER_IRQ UM_END_ETH_IRQ + 10
>
> -#define LAST_IRQ RANDOM_IRQ
> +#define LAST_IRQ HRTIMER_IRQ
> #define NR_IRQS (LAST_IRQ + 1)
>
> #endif
> diff --git a/arch/um/include/shared/kern_util.h
> b/arch/um/include/shared/kern_util.h
> index 83a91f9..0282b36 100644
> --- a/arch/um/include/shared/kern_util.h
> +++ b/arch/um/include/shared/kern_util.h
> @@ -37,6 +37,7 @@ extern void initial_thread_cb(void (*proc)(void *), void
> *arg);
> extern int is_syscall(unsigned long addr);
>
> extern void timer_handler(int sig, struct siginfo *unused_si, struct
> uml_pt_regs *regs);
> +extern void hrtimer_handler(int sig, struct siginfo *unused_si, struct
> uml_pt_regs *regs);
>
> extern int start_uml(void);
> extern void paging_init(void);
> diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
> index 7f544f4..d4fefb9 100644
> --- a/arch/um/include/shared/os.h
> +++ b/arch/um/include/shared/os.h
> @@ -222,6 +222,7 @@ extern char *get_umid(void);
>
> /* signal.c */
> extern void timer_init(void);
> +extern void uml_hrtimer_init(void);
> extern void set_sigstack(void *sig_stack, int size);
> extern void remove_sigstack(void);
> extern void set_handler(int sig);
> @@ -245,8 +246,12 @@ extern void idle_sleep(unsigned long long nsecs);
> extern int set_interval(void);
> extern int timer_one_shot(int ticks);
> extern long long disable_timer(void);
> +extern long long timer_remain(void);
> extern void uml_idle_timer(void);
> +extern long long persistent_clock_emulation(void);
> extern long long os_nsecs(void);
> +extern long long os_vnsecs(void);
> +extern int itimer_init(void);
>
> /* skas/mem.c */
> extern long run_syscall_stub(struct mm_id * mm_idp,
> diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
> index f4c6fb1..d70c487 100644
> --- a/arch/um/kernel/irq.c
> +++ b/arch/um/kernel/irq.c
> @@ -529,11 +529,23 @@ static struct irq_chip SIGVTALRM_irq_type = {
> .irq_unmask = dummy,
> };
>
> +static struct irq_chip SIGUSR2_irq_type = {
> + .name = "SIGUSR2",
> + .irq_disable = dummy,
> + .irq_enable = dummy,
> + .irq_ack = dummy,
> + .irq_mask = dummy,
> + .irq_unmask = dummy,
> +};
> +
> +
> void __init init_IRQ(void)
> {
> int i;
>
> irq_set_chip_and_handler(TIMER_IRQ, &SIGVTALRM_irq_type,
> handle_edge_irq);
> + irq_set_chip_and_handler(HRTIMER_IRQ, &SIGUSR2_irq_type,
> handle_edge_irq);
> +
> for (i = 1; i < NR_IRQS - 1 ; i++)
> irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
> os_setup_epoll(MAX_EPOLL_EVENTS);
> diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
> index bbcef52..b7ebc00 100644
> --- a/arch/um/kernel/process.c
> +++ b/arch/um/kernel/process.c
> @@ -27,6 +27,7 @@
> #include <kern_util.h>
> #include <os.h>
> #include <skas.h>
> +#include <timer-internal.h>
>
> /*
> * This is a per-cpu array. A processor only modifies its entry and it only
> @@ -215,7 +216,11 @@ void arch_cpu_idle(void)
> unsigned long long nsecs;
>
> cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
> - nsecs = disable_timer();
> + /* there is no benefit whatsoever in disabling a pending
> + * hrtimer and setting a nanowait for the same value instead
> + * so we do timer disable + wait only for the tracing one here
> + */
> + nsecs = tracingtimer_disable();
> idle_sleep(nsecs);
> local_irq_enable();
> }
> diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
> index 117568d..88fa9c6 100644
> --- a/arch/um/kernel/time.c
> +++ b/arch/um/kernel/time.c
> @@ -1,4 +1,5 @@
> /*
> + * Copyright (C) 2012-2014 Cisco Systems
> * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
> * Licensed under the GPL
> */
> @@ -12,6 +13,8 @@
> #include <asm/param.h>
> #include <kern_util.h>
> #include <os.h>
> +#include <timer-internal.h>
> +
>
> void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs
> *regs)
> {
> @@ -22,6 +25,15 @@ void timer_handler(int sig, struct siginfo *unused_si,
> struct uml_pt_regs *regs)
> local_irq_restore(flags);
> }
>
> +void hrtimer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs
> *regs)
> +{
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + do_IRQ(HRTIMER_IRQ, regs);
> + local_irq_restore(flags);
> +}
> +
> static void itimer_set_mode(enum clock_event_mode mode,
> struct clock_event_device *evt)
> {
> @@ -44,7 +56,7 @@ static void itimer_set_mode(enum clock_event_mode mode,
> static int itimer_next_event(unsigned long delta,
> struct clock_event_device *evt)
> {
> - return timer_one_shot(delta + 1);
> + return timer_one_shot(delta);
> }
>
> static struct clock_event_device itimer_clockevent = {
> @@ -54,8 +66,11 @@ static struct clock_event_device itimer_clockevent = {
> .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> .set_mode = itimer_set_mode,
> .set_next_event = itimer_next_event,
> - .shift = 32,
> + .shift = 0,
> + .max_delta_ns = 0xffffffff,
> + .min_delta_ns = TIMER_MIN_DELTA, //microsecond resolution should be
> enough for anyone, same as 640K RAM
> .irq = 0,
> + .mult = 1,
> };
>
> static irqreturn_t um_timer(int irq, void *dev)
> @@ -67,7 +82,7 @@ static irqreturn_t um_timer(int irq, void *dev)
>
> static cycle_t itimer_read(struct clocksource *cs)
> {
> - return os_nsecs() / 1000;
> + return os_nsecs() / TIMER_MULTIPLIER;
> }
>
> static struct clocksource itimer_clocksource = {
> @@ -82,17 +97,21 @@ static void __init setup_itimer(void)
> {
> int err;
>
> - err = request_irq(TIMER_IRQ, um_timer, 0, "timer", NULL);
> + err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
> if (err != 0)
> printk(KERN_ERR "register_timer : request_irq failed - "
> "errno = %d\n", -err);
> -
> - itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
> - itimer_clockevent.max_delta_ns =
> - clockevent_delta2ns(60 * HZ, &itimer_clockevent);
> - itimer_clockevent.min_delta_ns =
> - clockevent_delta2ns(1, &itimer_clockevent);
> - err = clocksource_register_hz(&itimer_clocksource, USEC_PER_SEC);
> + err = request_irq(HRTIMER_IRQ, um_timer, IRQF_DISABLED, "hr timer",
> NULL);
> + if (err != 0)
> + printk(KERN_ERR "register_timer : request_irq failed - "
> + "errno = %d\n", -err);
> + err = itimer_init();
> +
> + if (err != 0)
> + printk(KERN_ERR "init itimer failed - "
> + "errno = %d\n", -err);
> +
> + err = clocksource_register_hz(&itimer_clocksource,
> NSEC_PER_SEC/TIMER_MULTIPLIER);
> if (err) {
> printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
> return;
> @@ -102,7 +121,7 @@ static void __init setup_itimer(void)
>
> void read_persistent_clock(struct timespec *ts)
> {
> - long long nsecs = os_nsecs();
> + long long nsecs = persistent_clock_emulation();
>
> set_normalized_timespec(ts, nsecs / NSEC_PER_SEC,
> nsecs % NSEC_PER_SEC);
> @@ -111,5 +130,6 @@ void read_persistent_clock(struct timespec *ts)
> void __init time_init(void)
> {
> timer_init();
> + uml_hrtimer_init();
> late_time_init = setup_itimer;
> }
> diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
> index 905924b..85cff54 100644
> --- a/arch/um/os-Linux/signal.c
> +++ b/arch/um/os-Linux/signal.c
> @@ -23,7 +23,8 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct
> uml_pt_regs *) = {
> [SIGBUS] = bus_handler,
> [SIGSEGV] = segv_handler,
> [SIGIO] = sigio_handler,
> - [SIGVTALRM] = timer_handler };
> + [SIGVTALRM] = timer_handler,
> + [SIGUSR2] = hrtimer_handler };
>
> static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
> {
> @@ -58,6 +59,10 @@ static void sig_handler_common(int sig, struct siginfo
> *si, mcontext_t *mc)
> #define SIGVTALRM_BIT 1
> #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
>
> +#define SIGUSR2_BIT 1
> +#define SIGUSR2_MASK (1 << SIGUSR2_BIT)
> +
> +
> static int signals_enabled;
> static unsigned int signals_pending;
>
> @@ -89,6 +94,17 @@ static void real_alarm_handler(mcontext_t *mc)
> timer_handler(SIGVTALRM, NULL, ®s);
> }
>
> +static void real_hralarm_handler(mcontext_t *mc)
> +{
> + struct uml_pt_regs regs;
> +
> + if (mc != NULL)
> + get_regs_from_mc(®s, mc);
> + regs.is_user = 0;
> + hrtimer_handler(SIGUSR2, NULL, ®s);
> +}
> +
> +
> void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
> {
> int enabled;
> @@ -105,11 +121,33 @@ void alarm_handler(int sig, struct siginfo *unused_si,
> mcontext_t *mc)
> set_signals(enabled);
> }
>
> +void hralarm_handler(int sig, mcontext_t *mc)
> +{
> + int enabled;
> +
> + enabled = signals_enabled;
> + if (!signals_enabled) {
> + signals_pending |= SIGUSR2_MASK;
> + return;
> + }
> +
> + block_signals();
> +
> + real_hralarm_handler(mc);
> + set_signals(enabled);
> +}
> +
> +
> void timer_init(void)
> {
> set_handler(SIGVTALRM);
> }
>
> +void uml_hrtimer_init(void)
> +{
> + set_handler(SIGUSR2);
> +}
> +
> void set_sigstack(void *sig_stack, int size)
> {
> stack_t stack = ((stack_t) { .ss_flags = 0,
> @@ -129,7 +167,8 @@ static void (*handlers[_NSIG])(int sig, struct siginfo
> *si, mcontext_t *mc) = {
>
> [SIGIO] = sig_handler,
> [SIGWINCH] = sig_handler,
> - [SIGVTALRM] = alarm_handler
> + [SIGVTALRM] = alarm_handler,
> + [SIGUSR2] = hralarm_handler
> };
>
>
> @@ -189,6 +228,7 @@ void set_handler(int sig)
> sigaddset(&action.sa_mask, SIGVTALRM);
> sigaddset(&action.sa_mask, SIGIO);
> sigaddset(&action.sa_mask, SIGWINCH);
> + sigaddset(&action.sa_mask, SIGUSR2);
>
> if (sig == SIGSEGV)
> flags |= SA_NODEFER;
> @@ -283,6 +323,9 @@ void unblock_signals(void)
>
> if (save_pending & SIGVTALRM_MASK)
> real_alarm_handler(NULL);
> +
> + if (save_pending & SIGUSR2_MASK)
> + real_hralarm_handler(NULL);
> }
> }
>
> diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
> index d531879..64ccc64 100644
> --- a/arch/um/os-Linux/skas/process.c
> +++ b/arch/um/os-Linux/skas/process.c
> @@ -346,8 +346,7 @@ int start_userspace(unsigned long stub_stack)
>
> void userspace(struct uml_pt_regs *regs)
> {
> - struct itimerval timer;
> - unsigned long long nsecs, now;
> + unsigned long long nsecs;
> int err, status, op, pid = userspace_pid[0];
> /* To prevent races if using_sysemu changes under us.*/
> int local_using_sysemu;
> @@ -356,13 +355,11 @@ void userspace(struct uml_pt_regs *regs)
> /* Handle any immediate reschedules or signals */
> interrupt_end();
>
> - if (getitimer(ITIMER_VIRTUAL, &timer))
> - printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
> - nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
> - timer.it_value.tv_usec * UM_NSEC_PER_USEC;
> - nsecs += os_nsecs();
> -
> while (1) {
> +
> + nsecs = timer_remain();
> + nsecs += os_nsecs();
> +
> /*
> * This can legitimately fail if the process loads a
> * bogus value into a segment register. It will
> @@ -434,23 +431,18 @@ void userspace(struct uml_pt_regs *regs)
> relay_signal(SIGTRAP, (struct siginfo *)&si,
> regs);
> break;
> case SIGVTALRM:
> - now = os_nsecs();
> - if (now < nsecs)
> + if (nsecs < os_nsecs())
> break;
> block_signals();
> (*sig_info[sig])(sig, (struct siginfo *)&si,
> regs);
> unblock_signals();
> - nsecs = timer.it_value.tv_sec *
> - UM_NSEC_PER_SEC +
> - timer.it_value.tv_usec *
> - UM_NSEC_PER_USEC;
> - nsecs += os_nsecs();
> - break;
> + break;
> case SIGIO:
> case SIGILL:
> case SIGBUS:
> case SIGFPE:
> case SIGWINCH:
> + case SIGUSR2:
> block_signals();
> (*sig_info[sig])(sig, (struct siginfo *)&si,
> regs);
> unblock_signals();
> diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
> index e9824d5..f6eab4f 100644
> --- a/arch/um/os-Linux/time.c
> +++ b/arch/um/os-Linux/time.c
> @@ -1,4 +1,5 @@
> /*
> + * Copyright (C) 2012-2014 Cisco Systems
> * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
> * Licensed under the GPL
> */
> @@ -10,7 +11,53 @@
> #include <sys/time.h>
> #include <kern_util.h>
> #include <os.h>
> +#include <string.h>
> #include "internal.h"
> +#include <timer-internal.h>
> +
> +static timer_t event_high_res_timer = 0;
> +
> +static inline long long timeval_to_ns(const struct timeval *tv)
> +{
> + return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
> + tv->tv_usec * UM_NSEC_PER_USEC;
> +}
> +
> +static inline long long timespec_to_ns(const struct timespec *ts)
> +{
> + return ((long long) ts->tv_sec * UM_NSEC_PER_SEC) +
> + ts->tv_nsec;
> +}
> +
> +long long persistent_clock_emulation (void) {
> + struct timespec realtime_tp;
> +
> + clock_gettime(CLOCK_REALTIME, &realtime_tp);
> + return timespec_to_ns(&realtime_tp);
> +}
> +
> +
> +int itimer_init(void) {
> + struct sigevent sev, bbev;
> + sev.sigev_notify = SIGEV_SIGNAL;
> + sev.sigev_signo = SIGUSR2; /* note - hrtimer now has its own signal */
> + sev.sigev_value.sival_ptr = &event_high_res_timer;
> + if (timer_create(
> + CLOCK_MONOTONIC,
> + &sev,
> + &event_high_res_timer) == -1
> + ) {
> + printk("Failed to create Timer");
> + return -1;
> + } else {
> + printk("Event timer ID is 0x%lx\n", (long)
> event_high_res_timer);
> + }
> + return 0;
> +}
> +
> +/*
> +* This is used for tracing and cannot be removed at this point (TODO)
> +*/
>
> int set_interval(void)
> {
> @@ -24,61 +71,106 @@ int set_interval(void)
> return 0;
> }
>
> -int timer_one_shot(int ticks)
> +long long timer_remain (void)
> {
> - unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
> - unsigned long sec = usec / UM_USEC_PER_SEC;
> struct itimerval interval;
> + long long remain = 0;
> + if (getitimer(ITIMER_VIRTUAL, &interval)) {
> + printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
> + } else {
> + remain = timeval_to_ns(&interval.it_value);
> + }
> + return remain;
> +}
>
> - usec %= UM_USEC_PER_SEC;
> - interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
> +int timer_one_shot(int ticks)
> +{
> + struct itimerspec its;
> + unsigned long long nsec;
> + unsigned long sec;
>
> - if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
> - return -errno;
> +
> + nsec = (ticks + 1);
> +
> + sec = nsec / UM_NSEC_PER_SEC;
> +
> + nsec = nsec % UM_NSEC_PER_SEC;
> +
> + its.it_value.tv_sec = nsec / UM_NSEC_PER_SEC;
> + its.it_value.tv_nsec = nsec ;
> +
> + its.it_interval.tv_sec = 0;
> + its.it_interval.tv_nsec = 0; // we cheat here
> +
> + timer_settime(event_high_res_timer, 0, &its, NULL);
>
> return 0;
> }
>
> -/**
> - * timeval_to_ns - Convert timeval to nanoseconds
> - * @ts: pointer to the timeval variable to be converted
> - *
> - * Returns the scalar nanosecond representation of the timeval
> - * parameter.
> - *
> - * Ripped from linux/time.h because it's a kernel header, and thus
> - * unusable from here.
> - */
> -static inline long long timeval_to_ns(const struct timeval *tv)
> +long long hrtimer_disable(void)
> {
> - return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
> - tv->tv_usec * UM_NSEC_PER_USEC;
> + struct itimerspec its;
> +
> + memset(&its, 0, sizeof(struct itimerspec));
> + timer_settime(event_high_res_timer, 0, &its, &its);
> +
> + return its.it_value.tv_sec * UM_NSEC_PER_SEC + its.it_value.tv_nsec;
> }
>
> -long long disable_timer(void)
> +long long tracingtimer_disable(void)
> {
> - struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
> - long long remain, max = UM_NSEC_PER_SEC / UM_HZ;
> + struct itimerval itv;
>
> - if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
> - printk(UM_KERN_ERR "disable_timer - setitimer failed, "
> - "errno = %d\n", errno);
> + memset(&itv, 0, sizeof(struct itimerval));
> + setitimer(ITIMER_VIRTUAL, &itv, &itv);
>
> - remain = timeval_to_ns(&time.it_value);
> - if (remain > max)
> - remain = max;
> + return itv.it_value.tv_sec * UM_NSEC_PER_SEC + itv.it_value.tv_usec *
> 1000;
> +}
> +
> +long long disable_timer(void)
> +{
> + long long nsec;
> + long long tnsec;
> +
> + /*
> +
> + This is now fixed in the main idle loop so we really kill
> + both timers here to ensure that UML can exit cleanly and
> + not die on a spurious SIG_VTALRM
> +
> + */
> +
> +
> + nsec = hrtimer_disable();
> + tnsec = tracingtimer_disable();
> + if (nsec > tnsec) {
> + return tnsec;
> + } else {
> + return nsec;
> + }
> +}
> +
> +long long os_vnsecs(void)
> +{
> + struct timespec ts;
> +
> + clock_gettime(CLOCK_PROCESS_CPUTIME_ID,&ts);
> + return timespec_to_ns(&ts);
>
> - return remain;
> }
>
> long long os_nsecs(void)
> {
> - struct timeval tv;
>
> - gettimeofday(&tv, NULL);
> - return timeval_to_ns(&tv);
> + struct timespec ts;
> +
> + clock_gettime(CLOCK_MONOTONIC,&ts);
> + return timespec_to_ns(&ts);
> +
> }
>
> +
> +
> #ifdef UML_CONFIG_NO_HZ_COMMON
> static int after_sleep_interval(struct timespec *ts)
> {
> @@ -169,18 +261,24 @@ void idle_sleep(unsigned long long nsecs)
> struct timespec ts;
>
> /*
> - * nsecs can come in as zero, in which case, this starts a
> - * busy loop. To prevent this, reset nsecs to the tick
> - * interval if it is zero.
> + * We sleep here for an interval that is not greater than HZ
> + * We did not disable the timer in "disable" so if there is a timer
> + * active it will wake us up right on time instead of doing
> + * stupid things trying to program nanosleep in a race condition
> + * manner.
> */
> - if (nsecs == 0)
> - nsecs = UM_NSEC_PER_SEC / UM_HZ;
> +
> + if ((nsecs == 0) || (nsecs > UM_NSEC_PER_SEC / UM_HZ)) {
> + nsecs = UM_NSEC_PER_SEC / UM_HZ ;
> + }
>
> - nsecs = sleep_time(nsecs);
> ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC,
> .tv_nsec = nsecs % UM_NSEC_PER_SEC });
>
> - if (nanosleep(&ts, &ts) == 0)
> +
> + if (clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, &ts) == 0) {
> deliver_alarm();
> + }
> + set_interval();
> after_sleep_interval(&ts);
> }
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