| Message ID | 1328808329-27427-1-git-send-email-dmitry.antipov@linaro.org |
|---|---|
| State | New |
| Headers | show |
> + noirqtime [X86,ARM] Used to run time disable IRQ_TIME_ACCOUNTING, > + should give a negligible performance improvement. Can you reword the above "negligible performance improvement" above to something > + noirqtime [X86,ARM] Run time disables IRQ_TIME_ACCOUNTING and > + eliminates the timestamping on irq/softirq entry/exit. Otherwise, Acked-by: Venkatesh Pallipadi <venki@google.com> On Thu, Feb 9, 2012 at 9:25 AM, Dmitry Antipov <dmitry.antipov@linaro.org> wrote: > Generalize CONFIG_IRQ_TIME_ACCOUNTING between X86 and > ARM, move "noirqtime=" option to common debugging code. > For a bit of backward compatibility, X86-specific option > "tsc=noirqtime" is preserved, but issues a warning. > > Suggested-by: Yong Zhang <yong.zhang0@gmail.com> > Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk> > Suggested-by: Venki Pallipadi <venki@google.com> > Signed-off-by: Dmitry Antipov <dmitry.antipov@linaro.org> > --- > Documentation/kernel-parameters.txt | 9 +++++---- > arch/arm/kernel/sched_clock.c | 2 ++ > arch/x86/Kconfig | 11 ----------- > arch/x86/kernel/tsc.c | 12 ++++++------ > include/linux/sched.h | 17 ++++++++++------- > kernel/sched/core.c | 20 +++++++++++--------- > lib/Kconfig.debug | 12 ++++++++++++ > 7 files changed, 46 insertions(+), 37 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 033d4e6..666d20e 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -1790,6 +1790,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > noirqdebug [X86-32] Disables the code which attempts to detect and > disable unhandled interrupt sources. > > + noirqtime [X86,ARM] Used to run time disable IRQ_TIME_ACCOUNTING, > + should give a negligible performance improvement. > + > no_timer_check [X86,APIC] Disables the code which tests for > broken timer IRQ sources. > > @@ -2636,10 +2639,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > as the stability checks done at bootup. Used to enable > high-resolution timer mode on older hardware, and in > virtualized environment. > - [x86] noirqtime: Do not use TSC to do irq accounting. > - Used to run time disable IRQ_TIME_ACCOUNTING on any > - platforms where RDTSC is slow and this accounting > - can add overhead. > + [x86] noirqtime: obsoleted by "noirqtime" generic option, > + see it's documentation for details. > > turbografx.map[2|3]= [HW,JOY] > TurboGraFX parallel port interface > diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c > index 5416c7c..30b5f89 100644 > --- a/arch/arm/kernel/sched_clock.c > +++ b/arch/arm/kernel/sched_clock.c > @@ -144,6 +144,8 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) > */ > cd.epoch_ns = 0; > > + enable_sched_clock_irqtime(); > + > pr_debug("Registered %pF as sched_clock source\n", read); > } > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 5bed94e..4759676 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -805,17 +805,6 @@ config SCHED_MC > making when dealing with multi-core CPU chips at a cost of slightly > increased overhead in some places. If unsure say N here. > > -config IRQ_TIME_ACCOUNTING > - bool "Fine granularity task level IRQ time accounting" > - default n > - ---help--- > - Select this option to enable fine granularity task irq time > - accounting. This is done by reading a timestamp on each > - transitions between softirq and hardirq state, so there can be a > - small performance impact. > - > - If in doubt, say N here. > - > source "kernel/Kconfig.preempt" > > config X86_UP_APIC > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index a62c201..f1b2b63 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -103,14 +103,15 @@ int __init notsc_setup(char *str) > > __setup("notsc", notsc_setup); > > -static int no_sched_irq_time; > - > static int __init tsc_setup(char *str) > { > if (!strcmp(str, "reliable")) > tsc_clocksource_reliable = 1; > - if (!strncmp(str, "noirqtime", 9)) > - no_sched_irq_time = 1; > + if (!strncmp(str, "noirqtime", 9)) { > + printk(KERN_WARNING "tsc: tsc=noirqtime is " > + "obsolete, use noirqtime instead\n"); > + disable_sched_clock_irqtime(); > + } > return 1; > } > > @@ -978,8 +979,7 @@ void __init tsc_init(void) > /* now allow native_sched_clock() to use rdtsc */ > tsc_disabled = 0; > > - if (!no_sched_irq_time) > - enable_sched_clock_irqtime(); > + enable_sched_clock_irqtime(); > > lpj = ((u64)tsc_khz * 1000); > do_div(lpj, HZ); > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 7d379a6..9b13f79 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1961,13 +1961,16 @@ extern void sched_clock_idle_wakeup_event(u64 delta_ns); > #endif > > #ifdef CONFIG_IRQ_TIME_ACCOUNTING > -/* > - * An i/f to runtime opt-in for irq time accounting based off of sched_clock. > - * The reason for this explicit opt-in is not to have perf penalty with > - * slow sched_clocks. > - */ > -extern void enable_sched_clock_irqtime(void); > -extern void disable_sched_clock_irqtime(void); > +extern int sched_clock_irqtime; > +static inline void enable_sched_clock_irqtime(void) > +{ > + if (sched_clock_irqtime == -1) > + sched_clock_irqtime = 1; > +} > +static inline void disable_sched_clock_irqtime(void) > +{ > + sched_clock_irqtime = 0; > +} > #else > static inline void enable_sched_clock_irqtime(void) {} > static inline void disable_sched_clock_irqtime(void) {} > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 5255c9d..a7ec043 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -757,18 +757,20 @@ static DEFINE_PER_CPU(u64, cpu_hardirq_time); > static DEFINE_PER_CPU(u64, cpu_softirq_time); > > static DEFINE_PER_CPU(u64, irq_start_time); > -static int sched_clock_irqtime; > > -void enable_sched_clock_irqtime(void) > -{ > - sched_clock_irqtime = 1; > -} > +/* -1 if not initialized, 0 if disabled with "noirqtime" kernel option > + * or after unstable clock was detected, 1 if enabled and active. > + */ > +int sched_clock_irqtime = -1; > > -void disable_sched_clock_irqtime(void) > +static int __init irqtime_setup(char *str) > { > sched_clock_irqtime = 0; > + return 1; > } > > +__setup("noirqtime", irqtime_setup); > + > #ifndef CONFIG_64BIT > static DEFINE_PER_CPU(seqcount_t, irq_time_seq); > > @@ -822,7 +824,7 @@ void account_system_vtime(struct task_struct *curr) > s64 delta; > int cpu; > > - if (!sched_clock_irqtime) > + if (sched_clock_irqtime < 1) > return; > > local_irq_save(flags); > @@ -2853,7 +2855,7 @@ void account_process_tick(struct task_struct *p, int user_tick) > cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); > struct rq *rq = this_rq(); > > - if (sched_clock_irqtime) { > + if (sched_clock_irqtime > 0) { > irqtime_account_process_tick(p, user_tick, rq); > return; > } > @@ -2887,7 +2889,7 @@ void account_steal_ticks(unsigned long ticks) > void account_idle_ticks(unsigned long ticks) > { > > - if (sched_clock_irqtime) { > + if (sched_clock_irqtime > 0) { > irqtime_account_idle_ticks(ticks); > return; > } > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 8745ac7..236e814 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -299,6 +299,18 @@ config SCHEDSTATS > application, you can say N to avoid the very slight overhead > this adds. > > +config IRQ_TIME_ACCOUNTING > + bool "Fine granularity task level IRQ time accounting" > + depends on X86 || ARM > + default n > + ---help--- > + Select this option to enable fine granularity task irq time > + accounting. This is done by reading a timestamp on each > + transitions between softirq and hardirq state, so there can be a > + small performance impact. > + > + If in doubt, say N here. > + > config TIMER_STATS > bool "Collect kernel timers statistics" > depends on DEBUG_KERNEL && PROC_FS > -- > 1.7.7.6 >
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 033d4e6..666d20e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1790,6 +1790,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. noirqdebug [X86-32] Disables the code which attempts to detect and disable unhandled interrupt sources. + noirqtime [X86,ARM] Used to run time disable IRQ_TIME_ACCOUNTING, + should give a negligible performance improvement. + no_timer_check [X86,APIC] Disables the code which tests for broken timer IRQ sources. @@ -2636,10 +2639,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. as the stability checks done at bootup. Used to enable high-resolution timer mode on older hardware, and in virtualized environment. - [x86] noirqtime: Do not use TSC to do irq accounting. - Used to run time disable IRQ_TIME_ACCOUNTING on any - platforms where RDTSC is slow and this accounting - can add overhead. + [x86] noirqtime: obsoleted by "noirqtime" generic option, + see it's documentation for details. turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c index 5416c7c..30b5f89 100644 --- a/arch/arm/kernel/sched_clock.c +++ b/arch/arm/kernel/sched_clock.c @@ -144,6 +144,8 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) */ cd.epoch_ns = 0; + enable_sched_clock_irqtime(); + pr_debug("Registered %pF as sched_clock source\n", read); } diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 5bed94e..4759676 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -805,17 +805,6 @@ config SCHED_MC making when dealing with multi-core CPU chips at a cost of slightly increased overhead in some places. If unsure say N here. -config IRQ_TIME_ACCOUNTING - bool "Fine granularity task level IRQ time accounting" - default n - ---help--- - Select this option to enable fine granularity task irq time - accounting. This is done by reading a timestamp on each - transitions between softirq and hardirq state, so there can be a - small performance impact. - - If in doubt, say N here. - source "kernel/Kconfig.preempt" config X86_UP_APIC diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index a62c201..f1b2b63 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -103,14 +103,15 @@ int __init notsc_setup(char *str) __setup("notsc", notsc_setup); -static int no_sched_irq_time; - static int __init tsc_setup(char *str) { if (!strcmp(str, "reliable")) tsc_clocksource_reliable = 1; - if (!strncmp(str, "noirqtime", 9)) - no_sched_irq_time = 1; + if (!strncmp(str, "noirqtime", 9)) { + printk(KERN_WARNING "tsc: tsc=noirqtime is " + "obsolete, use noirqtime instead\n"); + disable_sched_clock_irqtime(); + } return 1; } @@ -978,8 +979,7 @@ void __init tsc_init(void) /* now allow native_sched_clock() to use rdtsc */ tsc_disabled = 0; - if (!no_sched_irq_time) - enable_sched_clock_irqtime(); + enable_sched_clock_irqtime(); lpj = ((u64)tsc_khz * 1000); do_div(lpj, HZ); diff --git a/include/linux/sched.h b/include/linux/sched.h index 7d379a6..9b13f79 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1961,13 +1961,16 @@ extern void sched_clock_idle_wakeup_event(u64 delta_ns); #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING -/* - * An i/f to runtime opt-in for irq time accounting based off of sched_clock. - * The reason for this explicit opt-in is not to have perf penalty with - * slow sched_clocks. - */ -extern void enable_sched_clock_irqtime(void); -extern void disable_sched_clock_irqtime(void); +extern int sched_clock_irqtime; +static inline void enable_sched_clock_irqtime(void) +{ + if (sched_clock_irqtime == -1) + sched_clock_irqtime = 1; +} +static inline void disable_sched_clock_irqtime(void) +{ + sched_clock_irqtime = 0; +} #else static inline void enable_sched_clock_irqtime(void) {} static inline void disable_sched_clock_irqtime(void) {} diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5255c9d..a7ec043 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -757,18 +757,20 @@ static DEFINE_PER_CPU(u64, cpu_hardirq_time); static DEFINE_PER_CPU(u64, cpu_softirq_time); static DEFINE_PER_CPU(u64, irq_start_time); -static int sched_clock_irqtime; -void enable_sched_clock_irqtime(void) -{ - sched_clock_irqtime = 1; -} +/* -1 if not initialized, 0 if disabled with "noirqtime" kernel option + * or after unstable clock was detected, 1 if enabled and active. + */ +int sched_clock_irqtime = -1; -void disable_sched_clock_irqtime(void) +static int __init irqtime_setup(char *str) { sched_clock_irqtime = 0; + return 1; } +__setup("noirqtime", irqtime_setup); + #ifndef CONFIG_64BIT static DEFINE_PER_CPU(seqcount_t, irq_time_seq); @@ -822,7 +824,7 @@ void account_system_vtime(struct task_struct *curr) s64 delta; int cpu; - if (!sched_clock_irqtime) + if (sched_clock_irqtime < 1) return; local_irq_save(flags); @@ -2853,7 +2855,7 @@ void account_process_tick(struct task_struct *p, int user_tick) cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); struct rq *rq = this_rq(); - if (sched_clock_irqtime) { + if (sched_clock_irqtime > 0) { irqtime_account_process_tick(p, user_tick, rq); return; } @@ -2887,7 +2889,7 @@ void account_steal_ticks(unsigned long ticks) void account_idle_ticks(unsigned long ticks) { - if (sched_clock_irqtime) { + if (sched_clock_irqtime > 0) { irqtime_account_idle_ticks(ticks); return; } diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8745ac7..236e814 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -299,6 +299,18 @@ config SCHEDSTATS application, you can say N to avoid the very slight overhead this adds. +config IRQ_TIME_ACCOUNTING + bool "Fine granularity task level IRQ time accounting" + depends on X86 || ARM + default n + ---help--- + Select this option to enable fine granularity task irq time + accounting. This is done by reading a timestamp on each + transitions between softirq and hardirq state, so there can be a + small performance impact. + + If in doubt, say N here. + config TIMER_STATS bool "Collect kernel timers statistics" depends on DEBUG_KERNEL && PROC_FS
Generalize CONFIG_IRQ_TIME_ACCOUNTING between X86 and ARM, move "noirqtime=" option to common debugging code. For a bit of backward compatibility, X86-specific option "tsc=noirqtime" is preserved, but issues a warning. Suggested-by: Yong Zhang <yong.zhang0@gmail.com> Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk> Suggested-by: Venki Pallipadi <venki@google.com> Signed-off-by: Dmitry Antipov <dmitry.antipov@linaro.org> --- Documentation/kernel-parameters.txt | 9 +++++---- arch/arm/kernel/sched_clock.c | 2 ++ arch/x86/Kconfig | 11 ----------- arch/x86/kernel/tsc.c | 12 ++++++------ include/linux/sched.h | 17 ++++++++++------- kernel/sched/core.c | 20 +++++++++++--------- lib/Kconfig.debug | 12 ++++++++++++ 7 files changed, 46 insertions(+), 37 deletions(-)