[dpdk-dev] [PATCH] eal: roundup tsc frequency when estimating it

[Pavan Nikhilesh]

When estimating tsc frequency using sleep/gettime round it up to the
nearest multiple of 10Mhz for more accuracy.

Signed-off-by: Pavan Nikhilesh <pbhagavat...@caviumnetworks.com>
---
 lib/librte_eal/common/eal_common_timer.c   |  4 ++--
 lib/librte_eal/common/include/rte_common.h | 10 ++++++++++
 lib/librte_eal/linuxapp/eal/eal_timer.c    |  2 +-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_timer.c 
b/lib/librte_eal/common/eal_common_timer.c
index dcf26bfea..1358bbed0 100644
--- a/lib/librte_eal/common/eal_common_timer.c
+++ b/lib/librte_eal/common/eal_common_timer.c
@@ -69,7 +69,7 @@ estimate_tsc_freq(void)
        /* assume that the sleep(1) will sleep for 1 second */
        uint64_t start = rte_rdtsc();
        sleep(1);
-       return rte_rdtsc() - start;
+       return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, 1E7);
 }
 
 void
@@ -83,7 +83,7 @@ set_tsc_freq(void)
        if (!freq)
                freq = estimate_tsc_freq();
 
-       RTE_LOG(DEBUG, EAL, "TSC frequency is ~%" PRIu64 " KHz\n", freq / 1000);
+       RTE_LOG(INFO, EAL, "TSC frequency is ~%" PRIu64 " Hz\n", freq);
        eal_tsc_resolution_hz = freq;
 }
 
diff --git a/lib/librte_eal/common/include/rte_common.h 
b/lib/librte_eal/common/include/rte_common.h
index 66cdf60b2..e374b16b1 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -248,6 +248,16 @@ static void __attribute__((destructor(RTE_PRIO(prio)), 
used)) func(void)
 #define RTE_ALIGN_MUL_FLOOR(v, mul) \
        ((v / ((typeof(v))(mul))) * (typeof(v))(mul))
 
+/**
+ * Macro to align a value to the nearest multiple of given value.
+ */
+#define RTE_ALIGN_MUL_NEAR(v, mul)                             \
+       ({                                                      \
+               typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul);    \
+               typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul);  \
+               (ceil - v) > (v - floor) ? floor: ceil;         \
+       })
+
 /**
  * Checks if a pointer is aligned to a given power-of-two value
  *
diff --git a/lib/librte_eal/linuxapp/eal/eal_timer.c 
b/lib/librte_eal/linuxapp/eal/eal_timer.c
index bc8f05199..864d6ef29 100644
--- a/lib/librte_eal/linuxapp/eal/eal_timer.c
+++ b/lib/librte_eal/linuxapp/eal/eal_timer.c
@@ -248,7 +248,7 @@ get_tsc_freq(void)
 
                double secs = (double)ns/NS_PER_SEC;
                tsc_hz = (uint64_t)((end - start)/secs);
-               return tsc_hz;
+               return RTE_ALIGN_MUL_NEAR(tsc_hz, 1E7);
        }
 #endif
        return 0;
-- 
2.19.2