From 6f43092441bda528dd38f2dc6c1e2522c5079fb7 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 31 Dec 2008 15:11:40 +0100 Subject: [PATCH] improve precision of idle time detection. Increase the precision of the idle time calculation that is exported to user space via /sys/devices/system/cpu/cpu/idle_time_us Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'arch/s390/kernel/smp.c') diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 6fc7854..3979a6f 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -851,9 +851,11 @@ static ssize_t show_idle_count(struct sys_device *dev, unsigned long long idle_count; idle = &per_cpu(s390_idle, dev->id); - spin_lock_irq(&idle->lock); + spin_lock(&idle->lock); idle_count = idle->idle_count; - spin_unlock_irq(&idle->lock); + if (idle->idle_enter) + idle_count++; + spin_unlock(&idle->lock); return sprintf(buf, "%llu\n", idle_count); } static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL); @@ -862,18 +864,17 @@ static ssize_t show_idle_time(struct sys_device *dev, struct sysdev_attribute *attr, char *buf) { struct s390_idle_data *idle; - unsigned long long new_time; + unsigned long long now, idle_time, idle_enter; idle = &per_cpu(s390_idle, dev->id); - spin_lock_irq(&idle->lock); - if (idle->in_idle) { - new_time = get_clock(); - idle->idle_time += new_time - idle->idle_enter; - idle->idle_enter = new_time; - } - new_time = idle->idle_time; - spin_unlock_irq(&idle->lock); - return sprintf(buf, "%llu\n", new_time >> 12); + spin_lock(&idle->lock); + now = get_clock(); + idle_time = idle->idle_time; + idle_enter = idle->idle_enter; + if (idle_enter != 0ULL && idle_enter < now) + idle_time += now - idle_enter; + spin_unlock(&idle->lock); + return sprintf(buf, "%llu\n", idle_time >> 12); } static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL); -- cgit v1.1 From c742b31c03f37c5c499178f09f57381aa6c70131 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 31 Dec 2008 15:11:42 +0100 Subject: [PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID The extract cpu time instruction (ectg) instruction allows the user process to get the current thread cputime without calling into the kernel. The code that uses the instruction needs to switch to the access registers mode to get access to the per-cpu info page that contains the two base values that are needed to calculate the current cputime from the CPU timer with the ectg instruction. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/s390/kernel/smp.c') diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 3979a6f..b3461e8 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -47,6 +47,7 @@ #include #include #include +#include #include "entry.h" /* @@ -506,6 +507,9 @@ static int __cpuinit smp_alloc_lowcore(int cpu) goto out; lowcore->extended_save_area_addr = (u32) save_area; } +#else + if (vdso_alloc_per_cpu(cpu, lowcore)) + goto out; #endif lowcore_ptr[cpu] = lowcore; return 0; @@ -528,6 +532,8 @@ static void smp_free_lowcore(int cpu) #ifndef CONFIG_64BIT if (MACHINE_HAS_IEEE) free_page((unsigned long) lowcore->extended_save_area_addr); +#else + vdso_free_per_cpu(cpu, lowcore); #endif free_page(lowcore->panic_stack - PAGE_SIZE); free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER); @@ -670,6 +676,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus) lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, lc_order); panic_stack = __get_free_page(GFP_KERNEL); async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER); + BUG_ON(!lowcore || !panic_stack || !async_stack); #ifndef CONFIG_64BIT if (MACHINE_HAS_IEEE) save_area = get_zeroed_page(GFP_KERNEL); @@ -683,6 +690,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus) #ifndef CONFIG_64BIT if (MACHINE_HAS_IEEE) lowcore->extended_save_area_addr = (u32) save_area; +#else + BUG_ON(vdso_alloc_per_cpu(smp_processor_id(), lowcore)); #endif set_prefix((u32)(unsigned long) lowcore); local_mcck_enable(); -- cgit v1.1