Re: [PATCH 3/4] cputime/powerpc/s390: make scaled cputime arch specific
From: Christian Borntraeger <hidden>
Date: 2016-11-02 09:11:45
Also in:
linuxppc-dev, lkml
On 10/31/2016 01:36 PM, Stanislaw Gruszka wrote:
Only s390 and powerpc have hardware facilities allowing to measure
cputimes scaled by frequency. On all other architectures
utimescaled/stimescaled are equal to utime/stime (however they are
accounted separately).
Patch remove {u,s}timescaled accounting on all architectures except
powerpc and s390, where those values are explicitly accounted on proper
places.If we remove it everywhere else (and assuming that there are no users then) I aks myself if we should remove this as well from s390. We already had to optimize this because the initial code caused some regressions (commit f341b8dff9 s390/vtime: limit MT scaling value updates). The code still adds a multiply and a divide to do_account_vtime (and 2 multiplies and 2 divides into vtime_account_irq_enter) which is still noticeable in perf annotate for switch intense workload. Martin are you aware of any user of that values?
quoted hunk ↗ jump to hunk
Signed-off-by: Stanislaw Gruszka <redacted> --- arch/ia64/kernel/time.c | 4 +- arch/powerpc/Kconfig | 1 + arch/powerpc/kernel/time.c | 6 +++- arch/s390/Kconfig | 1 + arch/s390/kernel/vtime.c | 9 ++++-- include/linux/kernel_stat.h | 4 +- include/linux/sched.h | 23 ++++++++++++---- kernel/fork.c | 2 + kernel/sched/cputime.c | 61 ++++++++++-------------------------------- 9 files changed, 50 insertions(+), 61 deletions(-)diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index 6f892b9..021f44a 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c@@ -68,7 +68,7 @@ void vtime_account_user(struct task_struct *tsk) if (ti->ac_utime) { delta_utime = cycle_to_cputime(ti->ac_utime); - account_user_time(tsk, delta_utime, delta_utime); + account_user_time(tsk, delta_utime); ti->ac_utime = 0; } }@@ -112,7 +112,7 @@ void vtime_account_system(struct task_struct *tsk) { cputime_t delta = vtime_delta(tsk); - account_system_time(tsk, 0, delta, delta); + account_system_time(tsk, 0, delta); } EXPORT_SYMBOL_GPL(vtime_account_system);diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 65fba4c..c7f120a 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig@@ -160,6 +160,7 @@ config PPC select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS select GENERIC_CPU_AUTOPROBE select HAVE_VIRT_CPU_ACCOUNTING + select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE select HAVE_ARCH_HARDENED_USERCOPY select HAVE_KERNEL_GZIPdiff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 8105198..be9751f 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c@@ -358,7 +358,8 @@ void vtime_account_system(struct task_struct *tsk) unsigned long delta, sys_scaled, stolen; delta = vtime_delta(tsk, &sys_scaled, &stolen); - account_system_time(tsk, 0, delta, sys_scaled); + account_system_time(tsk, 0, delta); + tsk->stimescaled += sys_scaled; if (stolen) account_steal_time(stolen); }@@ -391,7 +392,8 @@ void vtime_account_user(struct task_struct *tsk) acct->user_time = 0; acct->user_time_scaled = 0; acct->utime_sspurr = 0; - account_user_time(tsk, utime, utimescaled); + account_user_time(tsk, utime); + tsk->utimescaled += utimescaled; } #ifdef CONFIG_PPC32diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 426481d..028f97b 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig@@ -171,6 +171,7 @@ config S390 select SYSCTL_EXCEPTION_TRACE select TTY select VIRT_CPU_ACCOUNTING + select ARCH_HAS_SCALED_CPUTIME select VIRT_TO_BUS select HAVE_NMIdiff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c index 856e30d..90eeb7c 100644 --- a/arch/s390/kernel/vtime.c +++ b/arch/s390/kernel/vtime.c@@ -137,8 +137,10 @@ static int do_account_vtime(struct task_struct *tsk, int hardirq_offset) user_scaled = (user_scaled * mult) / div; system_scaled = (system_scaled * mult) / div; } - account_user_time(tsk, user, user_scaled); - account_system_time(tsk, hardirq_offset, system, system_scaled); + account_user_time(tsk, user); + tsk->utimescaled += user_scaled; + account_system_time(tsk, hardirq_offset, system) + tsk->stimescaled += system_scaled; steal = S390_lowcore.steal_timer; if ((s64) steal > 0) {@@ -202,7 +204,8 @@ void vtime_account_irq_enter(struct task_struct *tsk) system_scaled = (system_scaled * mult) / div; } - account_system_time(tsk, 0, system, system_scaled); + account_system_time(tsk, 0, system); + tsk->stimescaled += system_scaled; virt_timer_forward(system); }diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h index 44fda64..00f7768 100644 --- a/include/linux/kernel_stat.h +++ b/include/linux/kernel_stat.h@@ -78,8 +78,8 @@ static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu) return kstat_cpu(cpu).irqs_sum; } -extern void account_user_time(struct task_struct *, cputime_t, cputime_t); -extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t); +extern void account_user_time(struct task_struct *, cputime_t); +extern void account_system_time(struct task_struct *, int, cputime_t); extern void account_steal_time(cputime_t); extern void account_idle_time(cputime_t);diff --git a/include/linux/sched.h b/include/linux/sched.h index 348f51b..36a2c2e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h@@ -1627,7 +1627,10 @@ struct task_struct { int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ - cputime_t utime, stime, utimescaled, stimescaled; + cputime_t utime, stime; +#ifdef ARCH_HAS_SCALED_CPUTIME + cputime_t utimescaled, stimescaled; +#endif cputime_t gtime; struct prev_cputime prev_cputime; #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN@@ -2220,8 +2223,6 @@ static inline void put_task_struct(struct task_struct *t) #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN extern void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime); -extern void task_cputime_scaled(struct task_struct *t, - cputime_t *utimescaled, cputime_t *stimescaled); extern cputime_t task_gtime(struct task_struct *t); #else static inline void task_cputime(struct task_struct *t,@@ -2233,6 +2234,13 @@ static inline void task_cputime(struct task_struct *t, *stime = t->stime; } +static inline cputime_t task_gtime(struct task_struct *t) +{ + return t->gtime; +} +#endif + +#ifdef ARCH_HAS_SCALED_CPUTIME static inline void task_cputime_scaled(struct task_struct *t, cputime_t *utimescaled, cputime_t *stimescaled)@@ -2242,12 +2250,15 @@ static inline void task_cputime_scaled(struct task_struct *t, if (stimescaled) *stimescaled = t->stimescaled; } - -static inline cputime_t task_gtime(struct task_struct *t) +#else +static inline void task_cputime_scaled(struct task_struct *t, + cputime_t *utimescaled, + cputime_t *stimescaled) { - return t->gtime; + task_cputime(t, utimescaled, stimescaled); } #endif + extern void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st); extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);diff --git a/kernel/fork.c b/kernel/fork.c index 623259f..dbc9f60 100644 --- a/kernel/fork.c +++ b/kernel/fork.c@@ -1548,7 +1548,9 @@ static void posix_cpu_timers_init(struct task_struct *tsk) init_sigpending(&p->pending); p->utime = p->stime = p->gtime = 0; +#ifdef ARCH_HAS_SCALED_CPUTIME p->utimescaled = p->stimescaled = 0; +#endif prev_cputime_init(&p->prev_cputime); #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GENdiff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 3229c72..d427def 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c@@ -128,16 +128,13 @@ static inline void task_group_account_field(struct task_struct *p, int index, * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in user space since the last update - * @cputime_scaled: cputime scaled by cpu frequency */ -void account_user_time(struct task_struct *p, cputime_t cputime, - cputime_t cputime_scaled) +void account_user_time(struct task_struct *p, cputime_t cputime) { int index; /* Add user time to process. */ p->utime += cputime; - p->utimescaled += cputime_scaled; account_group_user_time(p, cputime); index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;@@ -153,16 +150,13 @@ void account_user_time(struct task_struct *p, cputime_t cputime, * Account guest cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in virtual machine since the last update - * @cputime_scaled: cputime scaled by cpu frequency */ -static void account_guest_time(struct task_struct *p, cputime_t cputime, - cputime_t cputime_scaled) +static void account_guest_time(struct task_struct *p, cputime_t cputime) { u64 *cpustat = kcpustat_this_cpu->cpustat; /* Add guest time to process. */ p->utime += cputime; - p->utimescaled += cputime_scaled; account_group_user_time(p, cputime); p->gtime += cputime;@@ -180,16 +174,13 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime, * Account system cpu time to a process and desired cpustat field * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in kernel space since the last update - * @cputime_scaled: cputime scaled by cpu frequency - * @target_cputime64: pointer to cpustat field that has to be updated + * @index: pointer to cpustat field that has to be updated */ static inline -void __account_system_time(struct task_struct *p, cputime_t cputime, - cputime_t cputime_scaled, int index) +void __account_system_time(struct task_struct *p, cputime_t cputime, int index) { /* Add system time to process. */ p->stime += cputime; - p->stimescaled += cputime_scaled; account_group_system_time(p, cputime); /* Add system time to cpustat. */@@ -204,15 +195,14 @@ void __account_system_time(struct task_struct *p, cputime_t cputime, * @p: the process that the cpu time gets accounted to * @hardirq_offset: the offset to subtract from hardirq_count() * @cputime: the cpu time spent in kernel space since the last update - * @cputime_scaled: cputime scaled by cpu frequency */ void account_system_time(struct task_struct *p, int hardirq_offset, - cputime_t cputime, cputime_t cputime_scaled) + cputime_t cputime) { int index; if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { - account_guest_time(p, cputime, cputime_scaled); + account_guest_time(p, cputime); return; }@@ -223,7 +213,7 @@ void account_system_time(struct task_struct *p, int hardirq_offset, else index = CPUTIME_SYSTEM; - __account_system_time(p, cputime, cputime_scaled, index); + __account_system_time(p, cputime, index); } /*@@ -410,15 +400,15 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, * So, we have to handle it separately here. * Also, p->stime needs to be updated for ksoftirqd. */ - __account_system_time(p, cputime, cputime, CPUTIME_SOFTIRQ); + __account_system_time(p, cputime, CPUTIME_SOFTIRQ); } else if (user_tick) { - account_user_time(p, cputime, cputime); + account_user_time(p, cputime); } else if (p == rq->idle) { account_idle_time(cputime); } else if (p->flags & PF_VCPU) { /* System time or guest time */ - account_guest_time(p, cputime, cputime); + account_guest_time(p, cputime); } else { - __account_system_time(p, cputime, cputime, CPUTIME_SYSTEM); + __account_system_time(p, cputime CPUTIME_SYSTEM); } }@@ -521,9 +511,9 @@ void account_process_tick(struct task_struct *p, int user_tick) cputime -= steal; if (user_tick) - account_user_time(p, cputime, cputime); + account_user_time(p, cputime); else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) - account_system_time(p, HARDIRQ_OFFSET, cputime, cputime); + account_system_time(p, HARDIRQ_OFFSET, cputime); else account_idle_time(cputime); }@@ -744,7 +734,7 @@ static void __vtime_account_system(struct task_struct *tsk) { cputime_t delta_cpu = get_vtime_delta(tsk); - account_system_time(tsk, irq_count(), delta_cpu, delta_cpu); + account_system_time(tsk, irq_count(), delta_cpu); } void vtime_account_system(struct task_struct *tsk)@@ -765,7 +755,7 @@ void vtime_account_user(struct task_struct *tsk) tsk->vtime_snap_whence = VTIME_SYS; if (vtime_delta(tsk)) { delta_cpu = get_vtime_delta(tsk); - account_user_time(tsk, delta_cpu, delta_cpu); + account_user_time(tsk, delta_cpu); } write_seqcount_end(&tsk->vtime_seqcount); }@@ -921,25 +911,4 @@ void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) if (stime) *stime += sdelta; } - -void task_cputime_scaled(struct task_struct *t, - cputime_t *utimescaled, cputime_t *stimescaled) -{ - cputime_t udelta, sdelta; - - if (!vtime_accounting_enabled()) { - if (utimescaled) - *utimescaled = t->utimescaled; - if (stimescaled) - *stimescaled = t->stimescaled; - return; - } - - fetch_task_cputime(t, utimescaled, stimescaled, - &t->utimescaled, &t->stimescaled, &udelta, &sdelta); - if (utimescaled) - *utimescaled += udelta; - if (stimescaled) - *stimescaled += sdelta; -} #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */