Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [PATCH v5 2/3] powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64 | Date | Thu, 2 Aug 2018 07:53:59 +0000 (UTC) |
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scaled cputime is only meaningfull when the processor has SPURR and/or PURR, which means only on PPC64.
Removing it on PPC32 significantly reduces the size of vtime_account_system() and vtime_account_idle() on an 8xx:
Before: 00000000 l F .text 000000a8 vtime_delta 00000280 g F .text 0000010c vtime_account_system 0000038c g F .text 00000048 vtime_account_idle
After: (vtime_delta gets inlined inside the two functions) 000001d8 g F .text 000000a0 vtime_account_system 00000278 g F .text 00000038 vtime_account_idle
In terms of performance, we also get approximatly 7% improvement on task switch. The following small benchmark app is run with perf stat:
void *thread(void *arg) { int i;
for (i = 0; i < atoi((char*)arg); i++) pthread_yield(); }
int main(int argc, char **argv) { pthread_t th1, th2;
pthread_create(&th1, NULL, thread, argv[1]); pthread_create(&th2, NULL, thread, argv[1]); pthread_join(th1, NULL); pthread_join(th2, NULL);
return 0; }
Before the patch:
Performance counter stats for 'chrt -f 98 ./sched 100000' (50 runs):
8228.476465 task-clock (msec) # 0.954 CPUs utilized ( +- 0.23% ) 200004 context-switches # 0.024 M/sec ( +- 0.00% )
After the patch:
Performance counter stats for 'chrt -f 98 ./sched 100000' (50 runs):
7649.070444 task-clock (msec) # 0.955 CPUs utilized ( +- 0.27% ) 200004 context-switches # 0.026 M/sec ( +- 0.00% )
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- v5: New (previous patch splitted in two parts)
arch/powerpc/Kconfig | 2 +- arch/powerpc/include/asm/accounting.h | 4 ++++ arch/powerpc/include/asm/cputime.h | 1 - arch/powerpc/kernel/time.c | 12 ++++++++++-- arch/powerpc/xmon/xmon.c | 4 ++++ 5 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 5eb4d969afbf..1f5ce708a650 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -137,7 +137,7 @@ config PPC select ARCH_HAS_PMEM_API if PPC64 select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_MEMBARRIER_CALLBACKS - select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE + select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC64 select ARCH_HAS_SG_CHAIN select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION) select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST diff --git a/arch/powerpc/include/asm/accounting.h b/arch/powerpc/include/asm/accounting.h index 3abcf98ed2e0..c607c5d835cc 100644 --- a/arch/powerpc/include/asm/accounting.h +++ b/arch/powerpc/include/asm/accounting.h @@ -15,8 +15,10 @@ struct cpu_accounting_data { /* Accumulated cputime values to flush on ticks*/ unsigned long utime; unsigned long stime; +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long utime_scaled; unsigned long stime_scaled; +#endif unsigned long gtime; unsigned long hardirq_time; unsigned long softirq_time; @@ -25,8 +27,10 @@ struct cpu_accounting_data { /* Internal counters */ unsigned long starttime; /* TB value snapshot */ unsigned long starttime_user; /* TB value on exit to usermode */ +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long startspurr; /* SPURR value snapshot */ unsigned long utime_sspurr; /* ->user_time when ->startspurr set */ +#endif }; #endif diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h index 133672744b2e..ae73dc8da2d4 100644 --- a/arch/powerpc/include/asm/cputime.h +++ b/arch/powerpc/include/asm/cputime.h @@ -61,7 +61,6 @@ static inline void arch_vtime_task_switch(struct task_struct *prev) struct cpu_accounting_data *acct0 = get_accounting(prev); acct->starttime = acct0->starttime; - acct->startspurr = acct0->startspurr; } #endif diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 6196bd7393a3..3b03731221c1 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -175,7 +175,7 @@ static void calc_cputime_factors(void) * Read the SPURR on systems that have it, otherwise the PURR, * or if that doesn't exist return the timebase value passed in. */ -static unsigned long read_spurr(unsigned long tb) +static inline unsigned long read_spurr(unsigned long tb) { if (cpu_has_feature(CPU_FTR_SPURR)) return mfspr(SPRN_SPURR); @@ -284,7 +284,8 @@ static inline u64 calculate_stolen_time(u64 stop_tb) static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct, unsigned long now, unsigned long stime) { - unsigned long stime_scaled; + unsigned long stime_scaled = 0; +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long nowscaled, deltascaled; unsigned long utime, utime_scaled; @@ -315,6 +316,7 @@ static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct, } } acct->utime_scaled += utime_scaled; +#endif return stime_scaled; } @@ -351,7 +353,9 @@ void vtime_account_system(struct task_struct *tsk) if ((tsk->flags & PF_VCPU) && !irq_count()) { acct->gtime += stime; +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME acct->utime_scaled += stime_scaled; +#endif } else { if (hardirq_count()) acct->hardirq_time += stime; @@ -360,7 +364,9 @@ void vtime_account_system(struct task_struct *tsk) else acct->stime += stime; +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME acct->stime_scaled += stime_scaled; +#endif } } EXPORT_SYMBOL_GPL(vtime_account_system); @@ -377,6 +383,7 @@ void vtime_account_idle(struct task_struct *tsk) static void vtime_flush_scaled(struct task_struct *tsk, struct cpu_accounting_data *acct) { +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME if (acct->utime_scaled) tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled); if (acct->stime_scaled) @@ -385,6 +392,7 @@ static void vtime_flush_scaled(struct task_struct *tsk, acct->utime_scaled = 0; acct->utime_sspurr = 0; acct->stime_scaled = 0; +#endif } /* diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index c7324e8469ee..cb7d1ce029c6 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -2442,11 +2442,15 @@ static void dump_one_paca(int cpu) DUMP(p, accounting.utime, "%#-*lx"); DUMP(p, accounting.stime, "%#-*lx"); +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME DUMP(p, accounting.utime_scaled, "%#-*lx"); +#endif DUMP(p, accounting.starttime, "%#-*lx"); DUMP(p, accounting.starttime_user, "%#-*lx"); +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME DUMP(p, accounting.startspurr, "%#-*lx"); DUMP(p, accounting.utime_sspurr, "%#-*lx"); +#endif DUMP(p, accounting.steal_time, "%#-*lx"); #undef DUMP -- 2.13.3
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