[dpdk-dev] [PATCH 17/22] timer: get TSC frequency from /proc/cpuinfo
Thomas Monjalon
thomas.monjalon at 6wind.com
Wed Mar 20 17:05:05 CET 2013
Frequency was guessed by sleeping 1 sec.
Now, read frequency from cpuinfo first.
Keep sleep method as fallback.
Acked-by: Ivan Boule <ivan.boule at 6wind.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon at 6wind.com>
---
lib/librte_eal/linuxapp/eal/eal_hpet.c | 47 ++++++++++++++++++++++++++++---
1 files changed, 42 insertions(+), 5 deletions(-)
diff --git a/lib/librte_eal/linuxapp/eal/eal_hpet.c b/lib/librte_eal/linuxapp/eal/eal_hpet.c
index de05151..d41e857 100644
--- a/lib/librte_eal/linuxapp/eal/eal_hpet.c
+++ b/lib/librte_eal/linuxapp/eal/eal_hpet.c
@@ -129,14 +129,51 @@ hpet_msb_inc(__attribute__((unused)) void *arg)
}
}
-static inline void
-set_rdtsc_freq(void)
+static uint64_t
+get_tsc_freq_from_cpuinfo(void)
{
- uint64_t start;
+ char line[256];
+ FILE *stream;
+ double dmhz;
+ uint64_t freq = 0;
+
+ stream = fopen("/proc/cpuinfo", "r");
+ if (!stream) {
+ RTE_LOG(WARNING, EAL, "WARNING: Unable to open /proc/cpuinfo\n");
+ return 0;
+ }
+
+ while (fgets(line, sizeof line, stream)) {
+ if (sscanf(line, "cpu MHz\t: %lf", &dmhz) == 1) {
+ freq = (uint64_t)(dmhz * 1000000UL);
+ break;
+ }
+ }
+
+ fclose(stream);
+ return freq;
+}
- start = rte_rdtsc();
+static uint64_t
+get_tsc_freq_from_sleep(void)
+{
+ uint64_t start = rte_rdtsc();
sleep(1);
- eal_hpet_resolution_hz = rte_rdtsc() - start;
+ return rte_rdtsc() - start;
+}
+
+static inline void
+set_rdtsc_freq(void)
+{
+ uint64_t freq;
+ freq = get_tsc_freq_from_cpuinfo();
+ if (!freq) {
+ RTE_LOG(WARNING, EAL, "WARNING: Cannot read CPU clock\n");
+ freq = get_tsc_freq_from_sleep();
+ }
+ RTE_LOG(INFO, EAL, "TSC clock @ %lu MHz\n",
+ (unsigned long) (freq / (1000000UL)));
+ eal_hpet_resolution_hz = freq;
eal_hpet_resolution_fs = (uint32_t)
((1.0 / eal_hpet_resolution_hz) / 1e-15);
}
--
1.7.2.5
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