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From: Stephen Hemminger <stephen@networkplumber.org>
To: dev@dpdk.org
Cc: Stephen Hemminger <stephen@networkplumber.org>,
	pbhagavatula@marvell.com, Keith Wiles <keith.wiles@intel.com>
Subject: [PATCH] eal: avoid issues in macro expansion of alignment
Date: Mon,  3 Jul 2023 11:55:51 -0700	[thread overview]
Message-ID: <20230703185551.57908-1-stephen@networkplumber.org> (raw)
In-Reply-To: <20210510194008.403-1-pbhagavatula@marvell.com>

RTE_ALIGN_MUL_NEAR is a macro so the cycle arguement could
get evaluated twice causing some potential skew.  Fix by
computing value once.

Suggested by patch to fix side effects.

Fixes: 5cbd14b3e5f9 ("eal: roundup TSC frequency when estimating")
Cc: pbhagavatula@marvell.com
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/eal/common/eal_common_timer.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/eal/common/eal_common_timer.c b/lib/eal/common/eal_common_timer.c
index 5686a5102b66..05614b0503cf 100644
--- a/lib/eal/common/eal_common_timer.c
+++ b/lib/eal/common/eal_common_timer.c
@@ -42,10 +42,14 @@ estimate_tsc_freq(void)
 	RTE_LOG(WARNING, EAL, "WARNING: TSC frequency estimated roughly"
 		" - clock timings may be less accurate.\n");
 	/* assume that the rte_delay_us_sleep() will sleep for 1 second */
-	uint64_t start = rte_rdtsc();
+	uint64_t start, elapsed;
+
+	start = rte_rdtsc();
 	rte_delay_us_sleep(US_PER_S);
+	elapsed = rte_rdtsc() - start;
+
 	/* Round up to 10Mhz. 1E7 ~ 10Mhz */
-	return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ);
+	return RTE_ALIGN_MUL_NEAR(elapsed, CYC_PER_10MHZ);
 }
 
 void
-- 
2.39.2


  parent reply	other threads:[~2023-07-03 18:55 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-09 17:18 [dpdk-dev] [PATCH 1/2] eal: fix side effects in align mul macros pbhagavatula
2021-05-09 17:18 ` [dpdk-dev] [PATCH 2/2] eal: fix side effects in ptr align macros pbhagavatula
2021-05-09 19:39   ` Stephen Hemminger
2021-05-10  9:50     ` [dpdk-dev] [EXT] " Pavan Nikhilesh Bhagavatula
2021-05-10 13:34       ` David Marchand
2021-05-10 14:02 ` [dpdk-dev] [PATCH v2 1/2] eal: fix side effects in align mul macros pbhagavatula
2021-05-10 14:02   ` [dpdk-dev] [PATCH v2 2/2] eal: fix side effects in ptr align macros pbhagavatula
2021-05-10 19:40   ` [dpdk-dev] [PATCH v3 1/2] eal: fix side effects in align mul macros pbhagavatula
2021-05-10 19:40     ` [dpdk-dev] [PATCH v3 2/2] eal: fix side effects in ptr align macros pbhagavatula
2021-05-11  2:12       ` Wang, Haiyue
2021-05-11  8:44         ` Pavan Nikhilesh Bhagavatula
2021-05-12  1:13           ` Wang, Haiyue
2023-07-03 18:55     ` Stephen Hemminger [this message]
2023-07-03 23:23       ` [PATCH v2] eal: avoid issues in macro expansion of alignment Stephen Hemminger
2023-07-04  8:43         ` Morten Brørup
2023-07-04 16:00           ` Stephen Hemminger
2023-07-04 22:16             ` Morten Brørup
2023-07-14 16:37               ` Stephen Hemminger
2023-07-04 16:01     ` [dpdk-dev] [PATCH v3 1/2] eal: fix side effects in align mul macros Stephen Hemminger

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