[dpdk-dev] eal: fix TSC resolution in hz for ppc_64 architecture
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Commit Message
From: Gowrishankar Muthukrishnan <gowrishankar.m@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@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(+)
Comments
-----Original Message-----
> Date: Thu, 21 Sep 2017 17:11:26 +0530
> From: Gowrishankar <gowrishankar.m@linux.vnet.ibm.com>
> To: dev@dpdk.org
> CC: Chao Zhu <chaozhu@linux.vnet.ibm.com>, Bruce Richardson
> <bruce.richardson@intel.com>, Konstantin Ananyev
> <konstantin.ananyev@intel.com>, Jerin Jacob
> <jerin.jacob@caviumnetworks.com>, Gowrishankar Muthukrishnan
> <gowrishankar.m@linux.vnet.ibm.com>
> Subject: [PATCH] eal: fix TSC resolution in hz for ppc_64 architecture
> X-Mailer: git-send-email 1.9.1
>
> From: Gowrishankar Muthukrishnan <gowrishankar.m@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@linux.vnet.ibm.com>
Hi Gowrishankar,
> ---
> 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
I guess you can use the below series to avoid ifdef clutter in common code.
Right?
http://dpdk.org/ml/archives/dev/2017-August/072805.html.
If yes, then you could resend the series with ppc_64 change.i.e
removing following patch and add yours.
http://dpdk.org/dev/patchwork/patch/27527/
> + 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
>
@@ -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;
}