[PATCH v2 01/12] test/pmd_perf: use compiler atomic builtins for polling sync

[Honnappa Nagarahalli]

<snip>

> 
> Convert rte_atomic usages to compiler atomic built-ins for polling sync in
> pmd_perf test cases.
> 
> Signed-off-by: Joyce Kong <joyce.kong at arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> ---
>  app/test/test_pmd_perf.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/app/test/test_pmd_perf.c b/app/test/test_pmd_perf.c index
> 1df86ce080..546384a50d 100644
> --- a/app/test/test_pmd_perf.c
> +++ b/app/test/test_pmd_perf.c
> @@ -10,7 +10,6 @@
>  #include <rte_cycles.h>
>  #include <rte_ethdev.h>
>  #include <rte_byteorder.h>
> -#include <rte_atomic.h>
>  #include <rte_malloc.h>
>  #include "packet_burst_generator.h"
>  #include "test.h"
> @@ -525,7 +524,7 @@ main_loop(__rte_unused void *args)
>  	return 0;
>  }
> 
> -static rte_atomic64_t start;
> +static uint64_t start;
> 
>  static inline int
>  poll_burst(void *args)
> @@ -563,8 +562,7 @@ poll_burst(void *args)
>  		num[portid] = pkt_per_port;
>  	}
> 
> -	while (!rte_atomic64_read(&start))
> -		;
> +	rte_wait_until_equal_64(&start, 1, __ATOMIC_ACQUIRE);
> 
>  	cur_tsc = rte_rdtsc();
>  	while (total) {
> @@ -616,15 +614,15 @@ exec_burst(uint32_t flags, int lcore)
>  	pkt_per_port = MAX_TRAFFIC_BURST;
>  	num = pkt_per_port * conf->nb_ports;
> 
> -	rte_atomic64_init(&start);
> -
>  	/* start polling thread, but not actually poll yet */
>  	rte_eal_remote_launch(poll_burst,
>  			      (void *)&pkt_per_port, lcore);
> 
>  	/* Only when polling first */
>  	if (flags == SC_BURST_POLL_FIRST)
> -		rte_atomic64_set(&start, 1);
> +		__atomic_store_n(&start, 1, __ATOMIC_RELAXED);
> +	else
> +		__atomic_store_n(&start, 0, __ATOMIC_RELAXED);
These lines need to be moved up before calling rte_eal_remote_launch, so that update to start is visible to the worker threads.

> 
>  	/* start xmit */
>  	i = 0;
> @@ -641,7 +639,7 @@ exec_burst(uint32_t flags, int lcore)
> 
>  	/* only when polling second  */
>  	if (flags == SC_BURST_XMIT_FIRST)
> -		rte_atomic64_set(&start, 1);
> +		__atomic_store_n(&start, 1, __ATOMIC_RELEASE);
> 
>  	/* wait for polling finished */
>  	diff_tsc = rte_eal_wait_lcore(lcore);
> --
> 2.25.1