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From: Jim Harris <james.r.harris@intel.com>
To: dev@dpdk.org, anatoly.burakov@intel.com
Date: Wed, 21 Aug 2019 10:29:58 -0700
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Subject: [dpdk-dev] [PATCH v2] timer: use rte_mp_msg to get freq from
primary process
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Ideally, get_tsc_freq_arch() is able to provide the
TSC rate using architecture-specific means. When that
is not possible, DPDK reverts to calculating the
TSC rate with a 100ms nanosleep or 1s sleep. The latter
occurs more frequently in VMs which often do not have
access to the data they need from arch-specific means
(CPUID leaf 0x15 or MSR 0xCE on x86).
In secondary processes, the extra 100ms is especially
noticeable and consumes the bulk of rte_eal_init()
execution time. So in secondary processes, if
we cannot get the TSC rate using get_tsc_freq_arch(),
try to get the TSC rate from the primary process
instead using rte_mp_msg. This is much faster than
100ms.
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>
Change-Id: I584419ed1c7d6f47841e0a0eb23f34c9f1186d35
---
lib/librte_eal/common/eal_common_timer.c | 62 ++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)
diff --git a/lib/librte_eal/common/eal_common_timer.c b/lib/librte_eal/common/eal_common_timer.c
index 145543de7..ad965455d 100644
--- a/lib/librte_eal/common/eal_common_timer.c
+++ b/lib/librte_eal/common/eal_common_timer.c
@@ -15,9 +15,17 @@
#include <rte_log.h>
#include <rte_cycles.h>
#include <rte_pause.h>
+#include <rte_eal.h>
+#include <rte_errno.h>
#include "eal_private.h"
+#define EAL_TIMER_MP "eal_timer_mp_sync"
+
+struct timer_mp_param {
+ uint64_t tsc_hz;
+};
+
/* The frequency of the RDTSC timer resolution */
static uint64_t eal_tsc_resolution_hz;
@@ -74,12 +82,58 @@ estimate_tsc_freq(void)
return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ);
}
+static uint64_t
+get_tsc_freq_from_primary(void)
+{
+ struct rte_mp_msg mp_req = {0};
+ struct rte_mp_reply mp_reply = {0};
+ struct timer_mp_param *r;
+ struct timespec ts = {.tv_sec = 1, .tv_nsec = 0};
+ uint64_t tsc_hz;
+
+ strcpy(mp_req.name, EAL_TIMER_MP);
+ if (rte_mp_request_sync(&mp_req, &mp_reply, &ts) ||
+ mp_reply.nb_received != 1) {
+ tsc_hz = 0;
+ } else {
+ r = (struct timer_mp_param *)mp_reply.msgs[0].param;
+ tsc_hz = r->tsc_hz;
+ }
+
+ free(mp_reply.msgs);
+ return tsc_hz;
+}
+
+static int
+timer_mp_primary(__attribute__((unused)) const struct rte_mp_msg *msg,
+ const void *peer)
+{
+ struct rte_mp_msg reply = {0};
+ struct timer_mp_param *r = (struct timer_mp_param *)reply.param;
+
+ r->tsc_hz = eal_tsc_resolution_hz;
+ strcpy(reply.name, EAL_TIMER_MP);
+ reply.len_param = sizeof(*r);
+
+ return rte_mp_reply(&reply, peer);
+}
+
void
set_tsc_freq(void)
{
uint64_t freq;
+ int rc;
freq = get_tsc_freq_arch();
+ if (!freq && rte_eal_process_type() != RTE_PROC_PRIMARY) {
+ /* We couldn't get the TSC frequency through arch-specific
+ * means. If this is a secondary process, try to get the
+ * TSC frequency from the primary process - this will
+ * be much faster than get_tsc_freq() or estimate_tsc_freq()
+ * below.
+ */
+ freq = get_tsc_freq_from_primary();
+ }
if (!freq)
freq = get_tsc_freq();
if (!freq)
@@ -87,6 +141,14 @@ set_tsc_freq(void)
RTE_LOG(DEBUG, EAL, "TSC frequency is ~%" PRIu64 " KHz\n", freq / 1000);
eal_tsc_resolution_hz = freq;
+ if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+ rc = rte_mp_action_register(EAL_TIMER_MP, timer_mp_primary);
+ if (rc && rte_errno != ENOTSUP) {
+ RTE_LOG(WARNING, EAL, "Could not register mp_action - "
+ "secondary processes will calculate TSC rate "
+ "independently.\n");
+ }
+ }
}
void rte_delay_us_callback_register(void (*userfunc)(unsigned int))