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eal: calibrate TSC only in primary process

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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>
This commit is contained in:
Jim Harris 2019-10-07 08:28:21 -07:00 committed by David Marchand
parent b36f587f01
commit b30b134f82
2 changed files with 18 additions and 0 deletions
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15
lib/librte_eal/common/eal_common_timer.c
View File

@ -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))

3
lib/librte_eal/common/eal_memcfg.h
View File

@ -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. */
};