[v3,2/5] latencystats: handle fractional cycles per ns
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Commit Message
The timer_hz is not always an integral number of nanoseconds.
For examples, cycles per nanoseconds on my test system is 2.8.
Fix by using floating point where needed.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
lib/latencystats/rte_latencystats.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
Comments
On Wed, Apr 17, 2024 at 10:07:24AM -0700, Stephen Hemminger wrote:
> The timer_hz is not always an integral number of nanoseconds.
> For examples, cycles per nanoseconds on my test system is 2.8.
> Fix by using floating point where needed.
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> lib/latencystats/rte_latencystats.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/lib/latencystats/rte_latencystats.c b/lib/latencystats/rte_latencystats.c
> index 9b345bfb33..fe8c3c563a 100644
> --- a/lib/latencystats/rte_latencystats.c
> +++ b/lib/latencystats/rte_latencystats.c
> @@ -19,10 +19,10 @@
> #define NS_PER_SEC 1E9
>
> /** Clock cycles per nano second */
> -static uint64_t
> +static float
> latencystat_cycles_per_ns(void)
> {
> - return rte_get_timer_hz() / NS_PER_SEC;
> + return (double)rte_get_timer_hz() / NS_PER_SEC;
> }
my feeling is this will generate a warning on msvc later double ->
float.
@@ -19,10 +19,10 @@
#define NS_PER_SEC 1E9
/** Clock cycles per nano second */
-static uint64_t
+static float
latencystat_cycles_per_ns(void)
{
- return rte_get_timer_hz() / NS_PER_SEC;
+ return (double)rte_get_timer_hz() / NS_PER_SEC;
}
RTE_LOG_REGISTER_DEFAULT(latencystat_logtype, INFO);
@@ -89,8 +89,7 @@ rte_latencystats_update(void)
for (i = 0; i < NUM_LATENCY_STATS; i++) {
stats_ptr = RTE_PTR_ADD(glob_stats,
lat_stats_strings[i].offset);
- values[i] = (uint64_t)floor((*stats_ptr)/
- latencystat_cycles_per_ns());
+ values[i] = floor(*stats_ptr / latencystat_cycles_per_ns());
}
ret = rte_metrics_update_values(RTE_METRICS_GLOBAL,
@@ -112,8 +111,7 @@ rte_latencystats_fill_values(struct rte_metric_value *values)
stats_ptr = RTE_PTR_ADD(glob_stats,
lat_stats_strings[i].offset);
values[i].key = i;
- values[i].value = (uint64_t)floor((*stats_ptr)/
- latencystat_cycles_per_ns());
+ values[i].value = floor(*stats_ptr / latencystat_cycles_per_ns());
}
}
@@ -237,7 +235,7 @@ rte_latencystats_init(uint64_t app_samp_intvl,
glob_stats = mz->addr;
rte_spinlock_init(&glob_stats->lock);
- samp_intvl = app_samp_intvl * latencystat_cycles_per_ns();
+ samp_intvl = floor(app_samp_intvl * latencystat_cycles_per_ns());
/** Register latency stats with stats library */
for (i = 0; i < NUM_LATENCY_STATS; i++)