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From: Isaac Boukris <iboukris@gmail.com>
To: dev@dpdk.org
Cc: stephen@networkplumber.org, bruce.richardson@intel.com,
roretzla@linux.microsoft.com, dmitry.kozliuk@gmail.com,
david.marchand@redhat.com, Isaac Boukris <iboukris@gmail.com>
Subject: [PATCH v4 1/2] timer: lower rounding of TSC estimation to 100KHz
Date: Wed, 2 Oct 2024 19:56:35 +0300
Message-ID: <20241002165840.341116-2-iboukris@gmail.com>
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In practice, the frequency is often not a nice round number, while
the estimation results are rather accurate, just a couple of KHz
away from the kernel's tsc_khz value, so it should suffice.
Rounding to 10MHz can cause a significant drift from real time,
up to a second per 10 minutes.
See also bugzilla: 959
Signed-off-by: Isaac Boukris <iboukris@gmail.com>
---
lib/eal/linux/eal_timer.c | 6 +++---
lib/eal/windows/eal_timer.c | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/lib/eal/linux/eal_timer.c b/lib/eal/linux/eal_timer.c
index 1cb1e92193..f56a7ae15b 100644
--- a/lib/eal/linux/eal_timer.c
+++ b/lib/eal/linux/eal_timer.c
@@ -192,7 +192,7 @@ get_tsc_freq(void)
{
#ifdef CLOCK_MONOTONIC_RAW
#define NS_PER_SEC 1E9
-#define CYC_PER_10MHZ 1E7
+#define CYC_PER_100KHZ 1E5
struct timespec sleeptime = {.tv_nsec = NS_PER_SEC / 10 }; /* 1/10 second */
@@ -209,8 +209,8 @@ get_tsc_freq(void)
double secs = (double)ns/NS_PER_SEC;
tsc_hz = (uint64_t)((end - start)/secs);
- /* Round up to 10Mhz. 1E7 ~ 10Mhz */
- return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_10MHZ);
+ /* Round up to 100Khz. 1E5 ~ 100Khz */
+ return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_100KHZ);
}
#endif
return 0;
diff --git a/lib/eal/windows/eal_timer.c b/lib/eal/windows/eal_timer.c
index b070cb7751..4003541b08 100644
--- a/lib/eal/windows/eal_timer.c
+++ b/lib/eal/windows/eal_timer.c
@@ -12,7 +12,7 @@
#include "eal_private.h"
#define US_PER_SEC 1E6
-#define CYC_PER_10MHZ 1E7
+#define CYC_PER_100KHZ 1E5
void
rte_delay_us_sleep(unsigned int us)
@@ -81,8 +81,8 @@ get_tsc_freq(void)
double secs = ((double)elapsed_us.QuadPart)/US_PER_SEC;
tsc_hz = (uint64_t)((end - start)/secs);
- /* Round up to 10Mhz. 1E7 ~ 10Mhz */
- return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_10MHZ);
+ /* Round up to 100Khz. 1E5 ~ 100Khz */
+ return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_100KHZ);
}
--
2.45.0