* DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
@ 2017-03-02 13:36 Rafał Miłecki
2017-03-02 14:13 ` Russell King - ARM Linux
2017-03-02 14:13 ` Rabin Vincent
0 siblings, 2 replies; 4+ messages in thread
From: Rafał Miłecki @ 2017-03-02 13:36 UTC (permalink / raw)
To: Rabin Vincent, Daniel Lezcano, linux-arm-kernel, linux-kernel
Cc: Srinivas Kandagatla, Maxime Coquelin, Patrice Chotard, tglx,
Hauke Mehrtens
Hi,
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 :)
Boot log from 4.9.13
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.9.13 (zajec@linux-samsung.lan) (gcc version 5.4.0 (LEDE GCC 5.4.0 r3346+1-9eacb9d7fc) ) #0 SMP Wed Mar 1 14:40:17 2017
[ 0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt:Machine model: SmartRG SR400ac
[ 0.000000] earlycon: ns16550 at MMIO 0x18000300 (options '')
[ 0.000000] bootconsole [ns16550] enabled
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] Hit pending asynchronous external abort (FSR=0x00001c06) during first unmask, this is most likely caused by a firmware/bootloader bug.
[ 0.000000] percpu: Embedded 12 pages/cpu @c6dd7000 s17868 r8192 d23092 u49152
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65280
[ 0.000000] Kernel command line: console=ttyS0,115200 earlycon
[ 0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Memory: 254860K/262144K available (3409K kernel code, 104K rwdata, 892K rodata, 228K init, 293K bss, 7284K reserved, 0K cma-reserved, 131072K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xc8800000 - 0xff800000 ( 880 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xc8000000 ( 128 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc035ca48 (3411 kB)
[ 0.000000] .init : 0xc043d000 - 0xc0476000 ( 228 kB)
[ 0.000000] .data : 0xc0476000 - 0xc0490180 ( 105 kB)
[ 0.000000] .bss : 0xc0490180 - 0xc04d95e0 ( 294 kB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
[ 0.000000] Hierarchical RCU implementation.
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] L2C: DT/platform modifies aux control register: 0x0a130000 -> 0x0a530000
[ 0.000000] L2C-310 enabling early BRESP for Cortex-A9
[ 0.000000] L2C-310 full line of zeros enabled for Cortex-A9
[ 0.000000] L2C-310 ID prefetch enabled, offset 1 lines
[ 0.000000] L2C-310 dynamic clock gating enabled, standby mode enabled
[ 0.000000] L2C-310 cache controller enabled, 16 ways, 256 kB
[ 0.000000] L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x7e530001
[ 0.000016] sched_clock: 64 bits at 400MHz, resolution 2ns, wraps every 4398046511103ns
[ 0.008678] clocksource: arm_global_timer: mask: 0xffffffffffffffff max_cycles: 0x5c4093a7d1, max_idle_ns: 440795210635 ns
[ 0.020820] Calibrating delay loop... 1594.16 BogoMIPS (lpj=7970816)
[ 0.113646] pid_max: default: 32768 minimum: 301
[ 0.118723] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.125908] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.134089] CPU: Testing write buffer coherency: ok
[ 0.139608] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.145842] Setting up static identity map for 0x82a0 - 0x82d4
[ 0.190681] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.190806] Brought up 2 CPUs
[ 0.200022] SMP: Total of 2 processors activated (3188.32 BogoMIPS).
Boot log from 4.9.13 with bbaa06702719 reverted
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.9.13 (zajec@linux-samsung.lan) (gcc version 5.4.0 (LEDE GCC 5.4.0 r3346+1-9eacb9d7fc) ) #0 SMP Wed Mar 1 14:40:17 2017
[ 0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt:Machine model: SmartRG SR400ac
[ 0.000000] earlycon: ns16550 at MMIO 0x18000300 (options '')
[ 0.000000] bootconsole [ns16550] enabled
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] Hit pending asynchronous external abort (FSR=0x00001c06) during first unmask, this is most likely caused by a firmware/bootloader bug.
[ 0.000000] percpu: Embedded 12 pages/cpu @c6dd7000 s17868 r8192 d23092 u49152
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65280
[ 0.000000] Kernel command line: console=ttyS0,115200 earlycon
[ 0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Memory: 254860K/262144K available (3409K kernel code, 104K rwdata, 892K rodata, 228K init, 293K bss, 7284K reserved, 0K cma-reserved, 131072K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xc8800000 - 0xff800000 ( 880 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xc8000000 ( 128 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc035ca68 (3411 kB)
[ 0.000000] .init : 0xc043d000 - 0xc0476000 ( 228 kB)
[ 0.000000] .data : 0xc0476000 - 0xc0490180 ( 105 kB)
[ 0.000000] .bss : 0xc0490180 - 0xc04d95e0 ( 294 kB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
[ 0.000000] Hierarchical RCU implementation.
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] L2C: DT/platform modifies aux control register: 0x0a130000 -> 0x0a530000
[ 0.000000] L2C-310 enabling early BRESP for Cortex-A9
[ 0.000000] L2C-310 full line of zeros enabled for Cortex-A9
[ 0.000000] L2C-310 ID prefetch enabled, offset 1 lines
[ 0.000000] L2C-310 dynamic clock gating enabled, standby mode enabled
[ 0.000000] L2C-310 cache controller enabled, 16 ways, 256 kB
[ 0.000000] L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x7e530001
[ 0.000015] sched_clock: 64 bits at 400MHz, resolution 2ns, wraps every 4398046511103ns
[ 0.008567] clocksource: arm_global_timer: mask: 0xffffffffffffffff max_cycles: 0x5c4093a7d1, max_idle_ns: 440795210635 ns
[ 0.020571] Switching to timer-based delay loop, resolution 2ns
[ 0.027082] Calibrating delay loop (skipped), value calculated using timer frequency.. 800.00 BogoMIPS (lpj=4000000)
[ 0.038359] pid_max: default: 32768 minimum: 301
[ 0.043367] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.050561] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.058779] CPU: Testing write buffer coherency: ok
[ 0.064363] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.070593] Setting up static identity map for 0x82a0 - 0x82d4
[ 0.078744] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.078858] Brought up 2 CPUs
[ 0.088254] SMP: Total of 2 processors activated (1600.00 BogoMIPS).
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
2017-03-02 13:36 DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") Rafał Miłecki
@ 2017-03-02 14:13 ` Russell King - ARM Linux
2017-03-02 17:46 ` Rafał Miłecki
2017-03-02 14:13 ` Rabin Vincent
1 sibling, 1 reply; 4+ messages in thread
From: Russell King - ARM Linux @ 2017-03-02 14:13 UTC (permalink / raw)
To: Rafał Miłecki
Cc: Rabin Vincent, Daniel Lezcano, linux-arm-kernel, linux-kernel,
Srinivas Kandagatla, tglx, Patrice Chotard, Hauke Mehrtens,
Maxime Coquelin
On Thu, Mar 02, 2017 at 02:36:23PM +0100, Rafał Miłecki wrote:
> Hi,
>
> 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?
Yes.
> Or should I be worried about this? I'm aware it's just BogoMIPS, but I
> still prefer to ask :)
It's *bogus*. Bogomips is the calibration value that the kernel uses
to achieve delays. It has nothing to do with the speed of the CPU on
modern systems that use a timer instead. (In that case, it's a
calibration value for the timer, rather than a calibration value for
the number of software loops required to achieve a delay.)
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
2017-03-02 13:36 DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") Rafał Miłecki
2017-03-02 14:13 ` Russell King - ARM Linux
@ 2017-03-02 14:13 ` Rabin Vincent
1 sibling, 0 replies; 4+ messages in thread
From: Rabin Vincent @ 2017-03-02 14:13 UTC (permalink / raw)
To: Rafał Miłecki
Cc: Daniel Lezcano, linux-arm-kernel, linux-kernel,
Srinivas Kandagatla, Maxime Coquelin, Patrice Chotard, tglx,
Hauke Mehrtens
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.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer")
2017-03-02 14:13 ` Russell King - ARM Linux
@ 2017-03-02 17:46 ` Rafał Miłecki
0 siblings, 0 replies; 4+ messages in thread
From: Rafał Miłecki @ 2017-03-02 17:46 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Rabin Vincent, Daniel Lezcano, linux-arm-kernel, linux-kernel,
Srinivas Kandagatla, tglx, Patrice Chotard, Hauke Mehrtens
On 03/02/2017 03:13 PM, Russell King - ARM Linux wrote:
> On Thu, Mar 02, 2017 at 02:36:23PM +0100, Rafał Miłecki wrote:
>> Hi,
>>
>> 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?
>
> Yes.
>
>> Or should I be worried about this? I'm aware it's just BogoMIPS, but I
>> still prefer to ask :)
>
> It's *bogus*. Bogomips is the calibration value that the kernel uses
> to achieve delays. It has nothing to do with the speed of the CPU on
> modern systems that use a timer instead. (In that case, it's a
> calibration value for the timer, rather than a calibration value for
> the number of software loops required to achieve a delay.)
Now I can sleep calm ;) thanks!
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-03-02 20:31 UTC | newest]
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2017-03-02 13:36 DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") Rafał Miłecki
2017-03-02 14:13 ` Russell King - ARM Linux
2017-03-02 17:46 ` Rafał Miłecki
2017-03-02 14:13 ` Rabin Vincent
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