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From: "Wiles, Keith" <keith.wiles@intel.com>
To: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>
Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
	"stephen@networkplumber.org" <stephen@networkplumber.org>,
	"thomas@monjalon.net" <thomas@monjalon.net>,
	"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2 2/2] eal: roundup tsc frequency when estimating it
Date: Sat, 16 Mar 2019 14:42:58 +0000	[thread overview]
Message-ID: <86480C64-4ECD-4F4D-968E-5716D02D7D83@intel.com> (raw)
Message-ID: <20190316144258.V-JfEipFehdU8vKiFaW73dkNEeW7BYLuWMWgWdDslrE@z> (raw)
In-Reply-To: <20190316070302.32432-2-pbhagavatula@marvell.com>



> On Mar 16, 2019, at 2:03 AM, Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com> wrote:
> 
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> 
> When estimating tsc frequency using sleep/gettime round it up to the
> nearest multiple of 10Mhz for more accuracy.
> 
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> ---
> Useful in case of ARM64 if we enable RTE_ARM_EAL_RDTSC_USE_PMU,
> get_tsc_freq_arch() will return 0 as there is no instruction to determine
> the clk of PMU and eal falls back to sleep(1).
> 
> lib/librte_eal/common/eal_common_timer.c | 4 ++--
> lib/librte_eal/linuxapp/eal/eal_timer.c  | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_eal/common/eal_common_timer.c b/lib/librte_eal/common/eal_common_timer.c
> index dcf26bfea..1358bbed0 100644
> --- a/lib/librte_eal/common/eal_common_timer.c
> +++ b/lib/librte_eal/common/eal_common_timer.c
> @@ -69,7 +69,7 @@ estimate_tsc_freq(void)
> 	/* assume that the sleep(1) will sleep for 1 second */
> 	uint64_t start = rte_rdtsc();
> 	sleep(1);
> -	return rte_rdtsc() - start;
> +	return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, 1E7);
> }
> 
> void
> @@ -83,7 +83,7 @@ set_tsc_freq(void)
> 	if (!freq)
> 		freq = estimate_tsc_freq();
> 
> -	RTE_LOG(DEBUG, EAL, "TSC frequency is ~%" PRIu64 " KHz\n", freq / 1000);
> +	RTE_LOG(INFO, EAL, "TSC frequency is ~%" PRIu64 " Hz\n", freq);
> 	eal_tsc_resolution_hz = freq;
> }
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_timer.c b/lib/librte_eal/linuxapp/eal/eal_timer.c
> index bc8f05199..864d6ef29 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_timer.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_timer.c
> @@ -248,7 +248,7 @@ get_tsc_freq(void)
> 
> 		double secs = (double)ns/NS_PER_SEC;
> 		tsc_hz = (uint64_t)((end - start)/secs);
> -		return tsc_hz;
> +		return RTE_ALIGN_MUL_NEAR(tsc_hz, 1E7);

Maybe I missed an email about this, but why would I want the TSC hz rounded here? I do not mind the macro just the fact that we are changing TSC hz value. If the TSC value is wrong then we need to fix the value, but I do not see it being wrong here.
> 	}
> #endif
> 	return 0;
> --
> 2.21.0
> 

Regards,
Keith


  parent reply	other threads:[~2019-03-16 14:43 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-29  8:32 [dpdk-dev] [PATCH] " Pavan Nikhilesh
2018-11-29  9:08 ` Jerin Jacob
2018-11-29 21:21 ` Stephen Hemminger
2018-11-30  7:17   ` Pavan Nikhilesh
2019-03-16  7:03 ` [dpdk-dev] [PATCH v2 1/2] eal: add macro to align value to the nearest multiple Pavan Nikhilesh Bhagavatula
2019-03-16  7:03   ` Pavan Nikhilesh Bhagavatula
2019-03-16  7:03   ` [dpdk-dev] [PATCH v2 2/2] eal: roundup tsc frequency when estimating it Pavan Nikhilesh Bhagavatula
2019-03-16  7:03     ` Pavan Nikhilesh Bhagavatula
2019-03-16 14:42     ` Wiles, Keith [this message]
2019-03-16 14:42       ` Wiles, Keith
2019-03-16 15:06       ` [dpdk-dev] [EXT] " Pavan Nikhilesh Bhagavatula
2019-03-16 15:06         ` Pavan Nikhilesh Bhagavatula
2019-03-16 17:18         ` Wiles, Keith
2019-03-16 17:18           ` Wiles, Keith
2019-03-16 17:56           ` Pavan Nikhilesh Bhagavatula
2019-03-16 17:56             ` Pavan Nikhilesh Bhagavatula
2019-03-16 18:22             ` Wiles, Keith
2019-03-16 18:22               ` Wiles, Keith
2019-03-16 18:27               ` Pavan Nikhilesh Bhagavatula
2019-03-16 18:27                 ` Pavan Nikhilesh Bhagavatula
2019-03-16 19:01 ` [dpdk-dev] [PATCH v3 1/2] eal: add macro to align value to the nearest multiple Pavan Nikhilesh Bhagavatula
2019-03-16 19:01   ` Pavan Nikhilesh Bhagavatula
2019-03-16 19:01   ` [dpdk-dev] [PATCH v3 2/2] eal: roundup tsc frequency when estimating Pavan Nikhilesh Bhagavatula
2019-03-16 19:01     ` Pavan Nikhilesh Bhagavatula
2019-03-27 22:43     ` Thomas Monjalon
2019-03-27 22:43       ` Thomas Monjalon

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