| Message ID | 20181119112917.4214-1-abrodkin@synopsys.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] clocksource/drivers/arc_timer: Utilize generic sched_clock | expand |
On 19/11/2018 12:29, Alexey Brodkin wrote: [ ... ] > arch/arc/Kconfig | 1 + > drivers/clocksource/Kconfig | 1 + > drivers/clocksource/arc_timer.c | 22 ++++++++++++++++++++++ > 3 files changed, 24 insertions(+) > > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig Can I have an Ack for the arch part ? Thanks -- Daniel
On 11/19/18 3:30 AM, Alexey Brodkin wrote: > 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> Acked-by: Vineet Gupta <vgupta@synopsys.com> Thx, -Vineet
On 19/11/2018 12:29, Alexey Brodkin wrote: > 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> > --- Applied, thanks.
Hi Daniel, On Mon, 2018-11-19 at 22:50 +0100, Daniel Lezcano wrote: > On 19/11/2018 12:29, Alexey Brodkin wrote: > > 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> > > --- > > Applied, thanks. Maybe a bit too late but I completely forgot to add stable tag into Cc list. Any chance to add it still? -Alexey
On 19/11/2018 22:53, Alexey Brodkin wrote: > Hi Daniel, > > On Mon, 2018-11-19 at 22:50 +0100, Daniel Lezcano wrote: >> On 19/11/2018 12:29, Alexey Brodkin wrote: >>> 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> >>> --- >> >> Applied, thanks. > > Maybe a bit too late but I completely forgot to add stable tag into Cc list. > Any chance to add it still? Yes, no problem, I've added it. [1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/tree/Documentation/process/stable-kernel-rules.rst?h=timers/core
On Mon, 2018-11-19 at 23:09 +0100, Daniel Lezcano wrote: > On 19/11/2018 22:53, Alexey Brodkin wrote: > > Hi Daniel, > > > > On Mon, 2018-11-19 at 22:50 +0100, Daniel Lezcano wrote: > > > On 19/11/2018 12:29, Alexey Brodkin wrote: > > > > 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> > > > > --- > > > > > > Applied, thanks. > > > > Maybe a bit too late but I completely forgot to add stable tag into Cc list. > > Any chance to add it still? > > Yes, no problem, I've added it. Cool, thanks! -Alexey
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index c9e2a1323536..74b5a654f664 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -26,6 +26,7 @@ config ARC select GENERIC_IRQ_SHOW select GENERIC_PCI_IOMAP select GENERIC_PENDING_IRQ if SMP + select GENERIC_SCHED_CLOCK select GENERIC_SMP_IDLE_THREAD select HAVE_ARCH_KGDB select HAVE_ARCH_TRACEHOOK diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 55c77e44bb2d..d9c8a779dd7d 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -290,6 +290,7 @@ config CLKSRC_MPS2 config ARC_TIMERS bool "Support for 32-bit TIMERn counters in ARC Cores" if COMPILE_TEST + depends on GENERIC_SCHED_CLOCK select TIMER_OF help These are legacy 32-bit TIMER0 and TIMER1 counters found on all ARC cores diff --git a/drivers/clocksource/arc_timer.c b/drivers/clocksource/arc_timer.c index 20da9b1d7f7d..b28970ca4a7a 100644 --- a/drivers/clocksource/arc_timer.c +++ b/drivers/clocksource/arc_timer.c @@ -23,6 +23,7 @@ #include <linux/cpu.h> #include <linux/of.h> #include <linux/of_irq.h> +#include <linux/sched_clock.h> #include <soc/arc/timers.h> #include <soc/arc/mcip.h> @@ -88,6 +89,11 @@ static u64 arc_read_gfrc(struct clocksource *cs) return (((u64)h) << 32) | l; } +static notrace u64 arc_gfrc_clock_read(void) +{ + return arc_read_gfrc(NULL); +} + static struct clocksource arc_counter_gfrc = { .name = "ARConnect GFRC", .rating = 400, @@ -111,6 +117,8 @@ static int __init arc_cs_setup_gfrc(struct device_node *node) if (ret) return ret; + sched_clock_register(arc_gfrc_clock_read, 64, arc_timer_freq); + return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq); } TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc); @@ -139,6 +147,11 @@ static u64 arc_read_rtc(struct clocksource *cs) return (((u64)h) << 32) | l; } +static notrace u64 arc_rtc_clock_read(void) +{ + return arc_read_rtc(NULL); +} + static struct clocksource arc_counter_rtc = { .name = "ARCv2 RTC", .rating = 350, @@ -170,6 +183,8 @@ static int __init arc_cs_setup_rtc(struct device_node *node) write_aux_reg(AUX_RTC_CTRL, 1); + sched_clock_register(arc_rtc_clock_read, 64, arc_timer_freq); + return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq); } TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc); @@ -185,6 +200,11 @@ static u64 arc_read_timer1(struct clocksource *cs) return (u64) read_aux_reg(ARC_REG_TIMER1_CNT); } +static notrace u64 arc_timer1_clock_read(void) +{ + return arc_read_timer1(NULL); +} + static struct clocksource arc_counter_timer1 = { .name = "ARC Timer1", .rating = 300, @@ -209,6 +229,8 @@ static int __init arc_cs_setup_timer1(struct device_node *node) write_aux_reg(ARC_REG_TIMER1_CNT, 0); write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH); + sched_clock_register(arc_timer1_clock_read, 32, arc_timer_freq); + return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq); }
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> --- Changes v2 -> v3: * Rebased on top of v4.20-rc3 * Moved GENERIC_SCHED_CLOCK to alphabetically-sorted location in arch/arc/Kconfig Changes v1 -> v2: * Timer read callbacks marked as "notrace" * ARC Timer1 explicitly described as 32-bit one on sched_clock_register() invocation arch/arc/Kconfig | 1 + drivers/clocksource/Kconfig | 1 + drivers/clocksource/arc_timer.c | 22 ++++++++++++++++++++++ 3 files changed, 24 insertions(+)