[RFC] eal: allow worker lcore stacks to be allocated from hugepage memory

[Honnappa Nagarahalli]

<snip>

> 
> Add support for using hugepages for worker lcore stack memory.  The intent is
> to improve performance by reducing stack memory related TLB misses and also
> by using memory local to the NUMA node of each lcore.
This is a good idea. Have you measured any performance differences with this patch? What kind of benefits do you see?

> 
> Platforms desiring to make use of this capability must enable the associated
> option flag and stack size settings in platform config files.
> ---
>  lib/eal/linux/eal.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c index
> 1ef263434a..4e1e5b6915 100644
> --- a/lib/eal/linux/eal.c
> +++ b/lib/eal/linux/eal.c
> @@ -1143,9 +1143,48 @@ rte_eal_init(int argc, char **argv)
> 
>  		lcore_config[i].state = WAIT;
> 
> +#ifdef RTE_EAL_NUMA_AWARE_LCORE_STACK
> +		/* Allocate NUMA aware stack memory and set pthread
> attributes */
> +		pthread_attr_t attr;
> +		void *stack_ptr =
> +			rte_zmalloc_socket("lcore_stack",
> +
> RTE_EAL_NUMA_AWARE_LCORE_STACK_SIZE,
> +
> RTE_EAL_NUMA_AWARE_LCORE_STACK_SIZE,
> +					   rte_lcore_to_socket_id(i));
> +
> +		if (stack_ptr == NULL) {
> +			rte_eal_init_alert("Cannot allocate stack memory");
May be worth adding more details to the error message, like lcore id.

> +			rte_errno = ENOMEM;
> +			return -1;
> +		}
> +
> +		if (pthread_attr_init(&attr) != 0) {
> +			rte_eal_init_alert("Cannot init pthread attributes");
> +			rte_errno = EINVAL;
EFAULT would be better.

> +			return -1;
> +		}
> +		if (pthread_attr_setstack(&attr,
> +					  stack_ptr,
> +
> RTE_EAL_NUMA_AWARE_LCORE_STACK_SIZE) != 0) {
> +			rte_eal_init_alert("Cannot set pthread stack
> attributes");
> +			rte_errno = ENOTSUP;
EFAULT would be better.

> +			return -1;
> +		}
> +
> +		/* create a thread for each lcore */
> +		ret = pthread_create(&lcore_config[i].thread_id, &attr,
> +				     eal_thread_loop, (void *)(uintptr_t)i);
> +
> +		if (pthread_attr_destroy(&attr) != 0) {
> +			rte_eal_init_alert("Cannot destroy pthread
> attributes");
> +			rte_errno = EFAULT;
> +			return -1;
> +		}
> +#else
>  		/* create a thread for each lcore */
>  		ret = pthread_create(&lcore_config[i].thread_id, NULL,
>  				     eal_thread_loop, (void *)(uintptr_t)i);
> +#endif
>  		if (ret != 0)
>  			rte_panic("Cannot create thread\n");
> 
> --
> 2.17.1