[v1] rte_timer: add rte_timer_next_ticks

  It is useful to know when the next timer will expire when
using rte_epoll_wait (or sleep when idle). This experimental
API provides a hook to query the number of ticks remaining.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
v1 - incorporate feedback from old RFC

 lib/librte_timer/rte_timer.c           | 27 ++++++++++++++++++++++++++
 lib/librte_timer/rte_timer.h           | 16 +++++++++++++++
 lib/librte_timer/rte_timer_version.map |  1 +
 3 files changed, 44 insertions(+)
  

Hi Stephen,

I added a comment  in-line.  With that change, it looks good to me:

Acked-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>

Regards,
Erik

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Monday, December 16, 2019 6:55 PM
> To: dev@dpdk.org
> Cc: Carrillo, Erik G <erik.g.carrillo@intel.com>; Stephen Hemminger
> <stephen@networkplumber.org>
> Subject: [PATCH v1] rte_timer: add rte_timer_next_ticks
> 
> It is useful to know when the next timer will expire when using
> rte_epoll_wait (or sleep when idle). This experimental API provides a hook
> to query the number of ticks remaining.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> v1 - incorporate feedback from old RFC
> 
>  lib/librte_timer/rte_timer.c           | 27 ++++++++++++++++++++++++++
>  lib/librte_timer/rte_timer.h           | 16 +++++++++++++++
>  lib/librte_timer/rte_timer_version.map |  1 +
>  3 files changed, 44 insertions(+)
> 
> diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c index
> ca88454ff68a..a1ed186cf591 100644
> --- a/lib/librte_timer/rte_timer.c
> +++ b/lib/librte_timer/rte_timer.c
> @@ -978,6 +978,33 @@ rte_timer_stop_all(uint32_t timer_data_id,
> unsigned int *walk_lcores,
>  	return 0;
>  }
> 
> +int64_t
> +rte_timer_next_ticks(void)
> +{
> +	unsigned int lcore_id = rte_lcore_id();
> +	struct rte_timer_data *timer_data;
> +	struct priv_timer *priv_timer;
> +	const struct rte_timer *tm;
> +	uint64_t cur_time;
> +	int64_t left = -ENOENT;
> +
> +	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id,
> timer_data, -EINVAL);
> +
> +	priv_timer = timer_data->priv_timer;
> +	cur_time = rte_get_timer_cycles();
> +
> +	rte_spinlock_lock(&priv_timer[lcore_id].list_lock);
> +	tm = priv_timer[lcore_id].pending_head.sl_next[0];
> +	if (tm) {
> +		left = tm->expire - cur_time;
> +		if (left < 0)
> +			left = 0;
> +	}
> +	rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
> +
> +	return left;
> +}
> +
>  /* dump statistics about timers */
>  static void
>  __rte_timer_dump_stats(struct rte_timer_data *timer_data __rte_unused,
> FILE *f) diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
> index 9dc5fc309249..c5031d0448ba 100644
> --- a/lib/librte_timer/rte_timer.h
> +++ b/lib/librte_timer/rte_timer.h
> @@ -331,6 +331,22 @@ void rte_timer_stop_sync(struct rte_timer *tim);
>   */
>  int rte_timer_pending(struct rte_timer *tim);
> 
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Time until the next timer

s/next timer/next timer on the current lcore

> + * This function gives the ticks until the next timer will be active.
> + *
> + * @return
> + *   - -EINVAL: invalid timer data instance identifier
> + *   - -ENOENT: no timer pending
> + *   - 0: a timer is pending and will run at next rte_timer_manage()
> + *   - >0: ticks until the next timer is ready
> + */
> +__rte_experimental
> +int64_t rte_timer_next_ticks(void);
> +
>  /**
>   * Manage the timer list and execute callback functions.
>   *
> diff --git a/lib/librte_timer/rte_timer_version.map
> b/lib/librte_timer/rte_timer_version.map
> index 2a59d3f081c4..4471cef92be5 100644
> --- a/lib/librte_timer/rte_timer_version.map
> +++ b/lib/librte_timer/rte_timer_version.map
> @@ -23,6 +23,7 @@ EXPERIMENTAL {
>  	rte_timer_alt_stop;
>  	rte_timer_data_alloc;
>  	rte_timer_data_dealloc;
> +	rte_timer_next_ticks;
>  	rte_timer_stop_all;
>  	rte_timer_subsystem_finalize;
>  };
> --
> 2.20.1
  

20/12/2019 23:43, Carrillo, Erik G:
> Hi Stephen,
> 
> I added a comment  in-line.  With that change, it looks good to me:
> 
> Acked-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>

Applied with below change, thanks.

> From: Stephen Hemminger <stephen@networkplumber.org>
> 
> > It is useful to know when the next timer will expire when using
> > rte_epoll_wait (or sleep when idle). This experimental API provides a hook
> > to query the number of ticks remaining.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> > + * Time until the next timer
> 
> s/next timer/next timer on the current lcore