[dpdk-stable] patch 'examples/timer: fix time interval' has been queued to stable release 20.11.2

[Xueming Li]

Hi,

FYI, your patch has been queued to stable release 20.11.2

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 06/14/21. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/steevenlee/dpdk

This queued commit can be viewed at:
https://github.com/steevenlee/dpdk/commit/3ce8842e183a1c2c9d077b5b510038bed49d6b87

Thanks.

Xueming Li <xuemingl at nvidia.com>

---
>From 3ce8842e183a1c2c9d077b5b510038bed49d6b87 Mon Sep 17 00:00:00 2001
From: Chengchang Tang <tangchengchang at huawei.com>
Date: Thu, 6 May 2021 17:29:36 +0800
Subject: [PATCH] examples/timer: fix time interval
Cc: Luca Boccassi <bluca at debian.org>

[ upstream commit 80aa15c4dff24e7a3b549f8dca37c16ae7220920 ]

Timer sample example assumes that the frequency of the timer is about
2Ghz to control the period of calling rte_timer_manage(). But this
assumption is easy to fail. For example. the frequency of tsc on ARM64
is much less than 2Ghz.

This patch uses the frequency of the current timer to calculate the
correct time interval to ensure consistent result on all platforms.

In addition, the rte_rdtsc() is replaced with the more recommended
rte_get_timer_cycles function in this patch.

Fixes: af75078fece3 ("first public release")

Signed-off-by: Chengchang Tang <tangchengchang at huawei.com>
Signed-off-by: Min Hu (Connor) <humin29 at huawei.com>
---
 examples/timer/main.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/examples/timer/main.c b/examples/timer/main.c
index d67301e3c4..d270ce49dc 100644
--- a/examples/timer/main.c
+++ b/examples/timer/main.c
@@ -18,8 +18,7 @@
 #include <rte_timer.h>
 #include <rte_debug.h>
 
-#define TIMER_RESOLUTION_CYCLES 20000000ULL /* around 10ms at 2 Ghz */
-
+static uint64_t timer_resolution_cycles;
 static struct rte_timer timer0;
 static struct rte_timer timer1;
 
@@ -66,15 +65,14 @@ lcore_mainloop(__rte_unused void *arg)
 
 	while (1) {
 		/*
-		 * Call the timer handler on each core: as we don't
-		 * need a very precise timer, so only call
-		 * rte_timer_manage() every ~10ms (at 2Ghz). In a real
-		 * application, this will enhance performances as
-		 * reading the HPET timer is not efficient.
+		 * Call the timer handler on each core: as we don't need a
+		 * very precise timer, so only call rte_timer_manage()
+		 * every ~10ms. In a real application, this will enhance
+		 * performances as reading the HPET timer is not efficient.
 		 */
-		cur_tsc = rte_rdtsc();
+		cur_tsc = rte_get_timer_cycles();
 		diff_tsc = cur_tsc - prev_tsc;
-		if (diff_tsc > TIMER_RESOLUTION_CYCLES) {
+		if (diff_tsc > timer_resolution_cycles) {
 			rte_timer_manage();
 			prev_tsc = cur_tsc;
 		}
@@ -100,8 +98,10 @@ main(int argc, char **argv)
 	rte_timer_init(&timer0);
 	rte_timer_init(&timer1);
 
-	/* load timer0, every second, on main lcore, reloaded automatically */
 	hz = rte_get_timer_hz();
+	timer_resolution_cycles = hz * 10 / 1000; /* around 10ms */
+
+	/* load timer0, every second, on main lcore, reloaded automatically */
 	lcore_id = rte_lcore_id();
 	rte_timer_reset(&timer0, hz, PERIODICAL, lcore_id, timer0_cb, NULL);
 
-- 
2.25.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-06-12 06:53:59.196702800 +0800
+++ 0100-examples-timer-fix-time-interval.patch	2021-06-12 06:53:56.450000000 +0800
@@ -1 +1 @@
-From 80aa15c4dff24e7a3b549f8dca37c16ae7220920 Mon Sep 17 00:00:00 2001
+From 3ce8842e183a1c2c9d077b5b510038bed49d6b87 Mon Sep 17 00:00:00 2001
@@ -4,0 +5,3 @@
+Cc: Luca Boccassi <bluca at debian.org>
+
+[ upstream commit 80aa15c4dff24e7a3b549f8dca37c16ae7220920 ]
@@ -18 +20,0 @@
-Cc: stable at dpdk.org