Re: [SPDK] Timer subsystem in SPDK application framework?

[Walker, Benjamin <benjamin.walker at intel.com>]

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On Tue, 2017-01-24 at 00:31 -0800, Naoki Iwakami wrote:
> Hi there,
> 
> I am using SPDK application framework (spdk_app_init() and so on),
> and struggling with figuring out the way to insert DPDK timer sub-
> system in the framework.
> 
> According to the DPDK documentation, you have to call function
> rte_timer_manage() periodically in lcores main_loop() in order to
> make the timer sub-system functioning properly.
> Could anyone advice where where I can find the lcore main loop in the
> SPDK app framework, and what is the recommended way to insert the
> rte_timer_manage() function?

The SPDK app framework spawns one thread per core for each core in the
core mask provided in the initialization options (called reactor_mask).
Each thread then sits in a tight loop polling queues for incoming
events and executing pollers. The implementation is in
lib/event/reactor.c.

Our app framework implements its own timers, so you don't need to use
the DPDK timers. You can just call

/**
 * \brief Register a poller on the given lcore.
 */
void spdk_poller_register(struct spdk_poller **ppoller,
			  spdk_poller_fn fn,
			  void *arg,
			  uint32_t lcore,
			  uint64_t period_microseconds);

and pass it a non-zero period.

If you really do need to use a DPDK timer, just register a poller using
the above function with a period of 0 and inside the spdk_poller_fn you
provide, call rte_timer_manage.

> 
> Regards,
> -- Naoki
> 
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