[dpdk-dev] [PATCH] eal: fix TSC resolution in hz for ppc_64 architecture

[Gowrishankar]

From: Gowrishankar Muthukrishnan <gowrishankar.m at linux.vnet.ibm.com>

In ppc_64, rte_rdtsc() returns timebase register value which increments
at independent timebase frequency and hence not related to lcore cpu
frequency to derive into. In this patch, we fix get_tsc_freq() to not
depend upon rte_rdtsc(), but obtain cpu current frequency from sysfs.

Signed-off-by: Gowrishankar Muthukrishnan <gowrishankar.m at linux.vnet.ibm.com>
---
 Note:
 * This patch would need minor port as per below patch (yet to upstream):
   http://dpdk.org/dev/patchwork/patch/27527/

 lib/librte_eal/linuxapp/eal/eal_timer.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/librte_eal/linuxapp/eal/eal_timer.c b/lib/librte_eal/linuxapp/eal/eal_timer.c
index afa32f5..b8775cc 100644
--- a/lib/librte_eal/linuxapp/eal/eal_timer.c
+++ b/lib/librte_eal/linuxapp/eal/eal_timer.c
@@ -55,8 +55,10 @@
 
 #include "eal_private.h"
 #include "eal_internal_cfg.h"
+#include "eal_filesystem.h"
 
 enum timer_source eal_timer_source = EAL_TIMER_HPET;
+static const char sys_cpu_dir[] = "/sys/devices/system/cpu";
 
 #ifdef RTE_LIBEAL_USE_HPET
 
@@ -269,6 +271,17 @@ struct eal_hpet_regs {
 uint64_t
 get_tsc_freq(void)
 {
+#ifdef RTE_ARCH_PPC_64
+	unsigned long cpu_hz;
+	char path[PATH_MAX];
+
+	snprintf(path, sizeof(path), "%s/cpu%d/cpufreq/cpuinfo_cur_freq",
+			sys_cpu_dir, rte_get_master_lcore());
+	if (eal_parse_sysfs_value(path, &cpu_hz) < 0)
+		RTE_LOG(WARNING, EAL, "Unable to parse %s\n",
+				path);
+	return cpu_hz*1000;
+#else
 #ifdef CLOCK_MONOTONIC_RAW
 #define NS_PER_SEC 1E9
 
@@ -290,6 +303,7 @@ struct eal_hpet_regs {
 		return tsc_hz;
 	}
 #endif
+#endif
 	return 0;
 }
 
-- 
1.9.1