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bf287607c8
linux/drivers/clocksource
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Alexey Brodkin bf287607c8 clocksource/drivers/arc_timer: Utilize generic sched_clock 
It turned out we used to use default implementation of sched_clock()
from kernel/sched/clock.c which was as precise as 1/HZ, i.e.
by default we had 10 msec granularity of time measurement.

Now given ARC built-in timers are clocked with the same frequency as
CPU cores we may get much higher precision of time tracking.

Thus we switch to generic sched_clock which really reads ARC hardware
counters.

This is especially helpful for measuring short events.
That's what we used to have:
------------------------------>8------------------------
$ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null

 Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello':

         10.000000      task-clock (msec)         #    2.832 CPUs utilized
                 1      context-switches          #    0.100 K/sec
                 1      cpu-migrations            #    0.100 K/sec
                63      page-faults               #    0.006 M/sec
           3049480      cycles                    #    0.305 GHz
           1091259      instructions              #    0.36  insn per cycle
            256828      branches                  #   25.683 M/sec
             27026      branch-misses             #   10.52% of all branches

       0.003530687 seconds time elapsed

       0.000000000 seconds user
       0.010000000 seconds sys
------------------------------>8------------------------

And now we'll see:
------------------------------>8------------------------
$ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null

 Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello':

          3.004322      task-clock (msec)         #    0.865 CPUs utilized
                 1      context-switches          #    0.333 K/sec
                 1      cpu-migrations            #    0.333 K/sec
                63      page-faults               #    0.021 M/sec
           2986734      cycles                    #    0.994 GHz
           1087466      instructions              #    0.36  insn per cycle
            255209      branches                  #   84.947 M/sec
             26002      branch-misses             #   10.19% of all branches

       0.003474829 seconds time elapsed

       0.003519000 seconds user
       0.000000000 seconds sys
------------------------------>8------------------------

Note how much more meaningful is the second output - time spent for
execution pretty much matches number of cycles spent (we're runnign
@ 1GHz here).

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2018-12-18 22:22:23 +01:00
..
acpi_pm.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
arc_timer.c clocksource/drivers/arc_timer: Utilize generic sched_clock 2018-12-18 22:22:23 +01:00
arm_arch_timer.c arm64: arch_timer: Add workaround for ARM erratum 1188873 2018-10-01 13:38:47 +01:00
arm_global_timer.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
armv7m_systick.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
asm9260_timer.c clocksource: Convert to using %pOFn instead of device_node.name 2018-10-03 14:36:52 +02:00
bcm2835_timer.c locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:08 +02:00
bcm_kona_timer.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
clksrc_st_lpc.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
clksrc-dbx500-prcmu.c clocksource/drivers/ux500: Drop Ux500 custom SCHED_CLOCK 2018-12-18 22:22:23 +01:00
clps711x-timer.c clocksource/drivers: Rename CLKSRC_OF to TIMER_OF 2017-06-14 12:01:03 +02:00
cs5535-clockevt.c clockevents/drivers/cs5535: Improve resilience to spurious interrupts 2017-10-20 13:41:52 +02:00
dummy_timer.c cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
dw_apb_timer_of.c clocksource/drivers/dw_apb: Add reset control 2018-10-07 14:16:35 +02:00
dw_apb_timer.c Merge branch 'clockevents/4.12' of https://git.linaro.org/people/daniel.lezcano/linux into timers/core 2017-04-17 10:55:14 +02:00
em_sti.c clocksource/drivers/em_sti: Fix error return codes in em_sti_probe() 2017-08-10 14:48:18 +02:00
exynos_mct.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
h8300_timer8.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
h8300_timer16.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
h8300_tpu.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
i8253.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
jcore-pit.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
Kconfig clocksource/drivers/arc_timer: Utilize generic sched_clock 2018-12-18 22:22:23 +01:00
Makefile Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-04 08:15:15 -08:00
meson6_timer.c clocksource/drivers/meson6_timer: Implement the ARM delay timer 2018-12-18 22:22:23 +01:00
mips-gic-timer.c clocksource/drivers/mips-gic-timer: Add pr_fmt and reword pr_* messages 2018-05-18 22:53:09 +02:00
mmio.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
mps2-timer.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
mxs_timer.c clocksource/drivers/mxs_timer: Switch to SPDX identifier 2018-05-23 07:39:09 +02:00
nomadik-mtu.c clocksource/drivers/ux500: Drop Ux500 custom SCHED_CLOCK 2018-12-18 22:22:23 +01:00
numachip.c x86/numachip: Add const and __initconst to numachip2_clockevent 2017-09-25 09:36:15 +02:00
pxa_timer.c clocksource: Convert to using %pOFn instead of device_node.name 2018-10-03 14:36:52 +02:00
renesas-ostm.c clocksource/drivers/renesas-ostm: Convert to SPDX identifiers 2018-10-03 14:36:53 +02:00
riscv_timer.c RISC-V: Use Linux logical CPU number instead of hartid 2018-10-22 17:03:37 -07:00
rockchip_timer.c clocksource/drivers/rockchip: pr_err() strings should end with newlines 2017-10-19 23:49:02 +02:00
samsung_pwm_timer.c clocksource/drivers: Rename CLKSRC_OF to TIMER_OF 2017-06-14 12:01:03 +02:00
scx200_hrt.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
sh_cmt.c clocksource/drivers/sh_cmt: Add R-Car gen3 support 2018-10-03 14:37:01 +02:00
sh_mtu2.c clocksource/drivers/sh_mtu2: Convert to SPDX identifiers 2018-10-03 14:36:55 +02:00
sh_tmu.c clocksource/drivers/sh_tmu: Convert to SPDX identifiers 2018-10-03 14:36:56 +02:00
sun4i_timer.c clocksource/drivers/sun4i: Switch to the timer-of common init 2017-06-26 18:32:04 +02:00
tango_xtal.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tcb_clksrc.c clocksource/drivers/tcb_clksrc: Fix clock speed message 2018-01-08 17:57:23 +01:00
tegra20_timer.c clockevents/drivers/tegra20: Remove obsolete inclusion of <asm/smp_twd.h> 2018-12-18 22:22:23 +01:00
timer-armada-370-xp.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-atcpit100.c clocksource/drivers: Set clockevent device cpumask to cpu_possible_mask 2018-07-26 11:26:30 +02:00
timer-atlas7.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-atmel-pit.c clocksource/drivers/timer-atmel-pit: Properly handle error cases 2018-09-27 12:01:45 +02:00
timer-atmel-st.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-cadence-ttc.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-digicolor.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-efm32.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-fsl-ftm.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-fttmr010.c clocksource/drivers/fttmr010: Fix set_next_event handler 2018-09-24 06:13:31 +02:00
timer-gx6605s.c clocksource/drivers/c-sky: Add gx6605s SOC system timer 2018-11-02 19:41:12 +01:00
timer-imx-gpt.c clocksource/drivers/imx-gpt: Remove unnecessary irq protection 2018-12-18 22:22:23 +01:00
timer-imx-tpm.c clocksource/drivers/timer-imx-tpm: Switch to SPDX identifier 2018-05-23 07:39:01 +02:00
timer-integrator-ap.c clocksource: Convert to using %pOFn instead of device_node.name 2018-10-03 14:36:52 +02:00
timer-keystone.c clocksource/drivers: Set clockevent device cpumask to cpu_possible_mask 2018-07-26 11:26:30 +02:00
timer-lpc32xx.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-mediatek.c clocksource/drivers/timer-mediatek: Add support for system timer 2018-07-26 11:26:34 +02:00
timer-mp-csky.c clocksource/drivers/c-sky: Add C-SKY SMP timer 2018-11-02 19:39:54 +01:00
timer-npcm7xx.c clocksource/drivers/npcm: Add NPCM7xx timer driver 2018-03-30 22:44:09 +02:00
timer-nps.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-of.c clocksource/drivers/timer-of: Don't request the resource by name 2018-01-08 17:57:24 +01:00
timer-of.h clocksource/drivers/timer-of: Store the device node pointer in 'struct timer_of' 2018-01-08 17:57:24 +01:00
timer-orion.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-owl.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-oxnas-rps.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-pistachio.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-prima2.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-probe.c clocksource: Convert to using %pOF instead of full_name 2017-08-31 15:56:17 +02:00
timer-qcom.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-sp804.c clocksource: Convert to using %pOFn instead of device_node.name 2018-10-03 14:36:52 +02:00
timer-sp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
timer-sprd.c clocksource/drivers/sprd: Register one always-on timer to compensate suspend time 2018-07-26 11:26:34 +02:00
timer-stm32.c clocksource/drivers/stm32: Fix error return code 2018-06-12 23:54:01 +02:00
timer-sun5i.c treewide/trivial: Remove ';;$' typo noise 2018-02-22 10:59:33 +01:00
timer-ti-32k.c clocksource/drivers/ti-32k: Add CLOCK_SOURCE_SUSPEND_NONSTOP flag for non-am43 SoCs 2018-09-13 15:23:35 +02:00
timer-ti-dm.c clocksource/drivers/timer-ti-dm: Remove the early platform driver registration 2018-12-18 22:22:23 +01:00
timer-u300.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-versatile.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-vf-pit.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-vt8500.c clocksource/drivers/timer-vt8500: Remove duplicate function name 2018-12-18 22:22:23 +01:00
timer-zevio.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00