eal: calibrate TSC only in primary process

This ensures secondary processes never have to calculate the TSC rate
themselves, which can be noticeable in VMs that don't have access to
arch-specific detection mechanism (such as CPUID leaf 0x15 or MSR 0xCE
on x86).

Since rte_mem_config is now internal to the EAL library, we can add
tsc_hz without ABI breakage concerns.

Reduces rte_eal_init() execution time in a secondary process from 165ms
to 66ms on my test system.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>

diff --git a/lib/librte_eal/common/eal_common_timer.c b/lib/librte_eal/common/eal_common_timer.c
index 145543d..fa9ee1b 100644 (file)
--- a/lib/librte_eal/common/eal_common_timer.c
+++ b/lib/librte_eal/common/eal_common_timer.c
@@ -15,8 +15,10 @@
 #include <rte_log.h>
 #include <rte_cycles.h>
 #include <rte_pause.h>
+#include <rte_eal.h>
 
 #include "eal_private.h"
+#include "eal_memcfg.h"
 
 /* The frequency of the RDTSC timer resolution */
 static uint64_t eal_tsc_resolution_hz;
@@ -77,8 +79,20 @@ estimate_tsc_freq(void)
 void
 set_tsc_freq(void)
 {
+       struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
        uint64_t freq;
 
+       if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
+               /*
+                * Just use the primary process calculated TSC rate in any
+                * secondary process.  It avoids any unnecessary overhead on
+                * systems where arch-specific frequency detection is not
+                * available.
+                */
+               eal_tsc_resolution_hz = mcfg->tsc_hz;
+               return;
+       }
+
        freq = get_tsc_freq_arch();
        if (!freq)
                freq = get_tsc_freq();
@@ -87,6 +101,7 @@ set_tsc_freq(void)
 
        RTE_LOG(DEBUG, EAL, "TSC frequency is ~%" PRIu64 " KHz\n", freq / 1000);
        eal_tsc_resolution_hz = freq;
+       mcfg->tsc_hz = freq;
 }
 
 void rte_delay_us_callback_register(void (*userfunc)(unsigned int))

diff --git a/lib/librte_eal/common/eal_memcfg.h b/lib/librte_eal/common/eal_memcfg.h
index aea9a35..0e468bb 100644 (file)
--- a/lib/librte_eal/common/eal_memcfg.h
+++ b/lib/librte_eal/common/eal_memcfg.h
@@ -69,6 +69,9 @@ struct rte_mem_config {
        uint32_t single_file_segments;
        /**< stored single file segments parameter. */
 
+       uint64_t tsc_hz;
+       /**< TSC rate */
+
        uint8_t dma_maskbits; /**< Keeps the more restricted dma mask. */
 };