[dpdk-dev] [PATCH v3 2/2] eal: roundup tsc frequency when estimating
Pavan Nikhilesh Bhagavatula
pbhagavatula at marvell.com
Sat Mar 16 20:01:54 CET 2019
From: Pavan Nikhilesh <pbhagavatula at marvell.com>
When estimating tsc frequency using sleep/gettime round it up to the
nearest multiple of 10Mhz for more accuracy.
Signed-off-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
Reviewed-by: Keith Wiles <keith.wiles at intel.com>
---
Useful in case of ARM64 if we enable RTE_ARM_EAL_RDTSC_USE_PMU,
get_tsc_freq_arch() will return 0 as there is no instruction to determine
the clk of PMU and eal falls back to sleep(1).
lib/librte_eal/common/eal_common_timer.c | 4 +++-
lib/librte_eal/linux/eal/eal_timer.c | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/lib/librte_eal/common/eal_common_timer.c b/lib/librte_eal/common/eal_common_timer.c
index dcf26bfea..68d67e684 100644
--- a/lib/librte_eal/common/eal_common_timer.c
+++ b/lib/librte_eal/common/eal_common_timer.c
@@ -64,12 +64,14 @@ rte_get_tsc_hz(void)
static uint64_t
estimate_tsc_freq(void)
{
+#define CYC_PER_10MHZ 1E7
RTE_LOG(WARNING, EAL, "WARNING: TSC frequency estimated roughly"
" - clock timings may be less accurate.\n");
/* assume that the sleep(1) will sleep for 1 second */
uint64_t start = rte_rdtsc();
sleep(1);
- return rte_rdtsc() - start;
+ /* Round up to 10Mhz. 1E7 ~ 10Mhz */
+ return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ);
}
void
diff --git a/lib/librte_eal/linux/eal/eal_timer.c b/lib/librte_eal/linux/eal/eal_timer.c
index bc8f05199..76ec17034 100644
--- a/lib/librte_eal/linux/eal/eal_timer.c
+++ b/lib/librte_eal/linux/eal/eal_timer.c
@@ -232,6 +232,7 @@ get_tsc_freq(void)
{
#ifdef CLOCK_MONOTONIC_RAW
#define NS_PER_SEC 1E9
+#define CYC_PER_10MHZ 1E7
struct timespec sleeptime = {.tv_nsec = NS_PER_SEC / 10 }; /* 1/10 second */
@@ -248,7 +249,8 @@ get_tsc_freq(void)
double secs = (double)ns/NS_PER_SEC;
tsc_hz = (uint64_t)((end - start)/secs);
- return tsc_hz;
+ /* Round up to 10Mhz. 1E7 ~ 10Mhz */
+ return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_10MHZ);
}
#endif
return 0;
--
2.21.0
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