From: rabin.vincent@axis.com (Rabin Vincent)
To: linux-arm-kernel@lists.infradead.org
Subject: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
Date: Thu, 2 Mar 2017 15:13:56 +0100 [thread overview]
Message-ID: <20170302141356.GC6763@axis.com> (raw)
In-Reply-To: <d22ec429-1a71-e56f-e1d7-28b066be8c1b@milecki.pl>
On Thu, Mar 02, 2017 at 02:36:23PM +0100, Rafa? Mi?ecki wrote:
> I just updated kernel on my SmartRG SR400ac (bcm4708-smartrg-sr400ac.dts) from
> 4.4 to 4.9 and noticed that this part of the log:
> [ 0.020820] Calibrating delay loop... 1594.16 BogoMIPS (lpj=7970816)
> (...)
> [ 0.190806] Brought up 2 CPUs
> [ 0.200022] SMP: Total of 2 processors activated (3188.32 BogoMIPS).
>
> became:
> [ 0.027082] Calibrating delay loop (skipped), value calculated using timer frequency.. 800.00 BogoMIPS (lpj=4000000)
> (...)
> [ 0.078858] Brought up 2 CPUs
> [ 0.088254] SMP: Total of 2 processors activated (1600.00 BogoMIPS).
>
> This is caused by commit bbaa06702719 ("clocksource/drivers/arm_global_timer:
> Register delay timer").
>
> Is this something expected? Or should I be worried about this? I'm aware it's
> just BogoMIPS, but I still prefer to ask :)
Yes, it's expected.
No, you shouldn't be worried.
It's even explained on Wikipedia:
https://en.wikipedia.org/wiki/BogoMips#Timer-based_delays
You can run the udelay test (CONFIG_TEST_UDELAY) if you want to make
sure that your delay loops are fine.
WARNING: multiple messages have this Message-ID (diff)
From: Rabin Vincent <rabin.vincent@axis.com>
To: "Rafał Miłecki" <rafal@milecki.pl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Srinivas Kandagatla <srinivas.kandagatla@gmail.com>,
Maxime Coquelin <maxime.coquelin@st.com>,
Patrice Chotard <patrice.chotard@st.com>,
tglx@linutronix.de, Hauke Mehrtens <hauke@hauke-m.de>
Subject: Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
Date: Thu, 2 Mar 2017 15:13:56 +0100 [thread overview]
Message-ID: <20170302141356.GC6763@axis.com> (raw)
In-Reply-To: <d22ec429-1a71-e56f-e1d7-28b066be8c1b@milecki.pl>
On Thu, Mar 02, 2017 at 02:36:23PM +0100, Rafał Miłecki wrote:
> I just updated kernel on my SmartRG SR400ac (bcm4708-smartrg-sr400ac.dts) from
> 4.4 to 4.9 and noticed that this part of the log:
> [ 0.020820] Calibrating delay loop... 1594.16 BogoMIPS (lpj=7970816)
> (...)
> [ 0.190806] Brought up 2 CPUs
> [ 0.200022] SMP: Total of 2 processors activated (3188.32 BogoMIPS).
>
> became:
> [ 0.027082] Calibrating delay loop (skipped), value calculated using timer frequency.. 800.00 BogoMIPS (lpj=4000000)
> (...)
> [ 0.078858] Brought up 2 CPUs
> [ 0.088254] SMP: Total of 2 processors activated (1600.00 BogoMIPS).
>
> This is caused by commit bbaa06702719 ("clocksource/drivers/arm_global_timer:
> Register delay timer").
>
> Is this something expected? Or should I be worried about this? I'm aware it's
> just BogoMIPS, but I still prefer to ask :)
Yes, it's expected.
No, you shouldn't be worried.
It's even explained on Wikipedia:
https://en.wikipedia.org/wiki/BogoMips#Timer-based_delays
You can run the udelay test (CONFIG_TEST_UDELAY) if you want to make
sure that your delay loops are fine.
next prev parent reply other threads:[~2017-03-02 14:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-02 13:36 DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") Rafał Miłecki
2017-03-02 13:36 ` Rafał Miłecki
2017-03-02 14:13 ` Russell King - ARM Linux
2017-03-02 14:13 ` Russell King - ARM Linux
2017-03-02 17:46 ` Rafał Miłecki
2017-03-02 17:46 ` Rafał Miłecki
2017-03-02 14:13 ` Rabin Vincent [this message]
2017-03-02 14:13 ` Rabin Vincent
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