From 0a71336b6a8858a525007c5b4e0d14ba57f9f315 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 11 Jan 2005 01:40:38 -0800 Subject: [PATCH] cputime: introduce cputime This patch introduces the concept of (virtual) cputime. Each architecture can define its method to measure cputime. The main idea is to define a cputime_t type and a set of operations on it (see asm-generic/cputime.h). Then use the type for utime, stime, cutime, cstime, it_virt_value, it_virt_incr, it_prof_value and it_prof_incr and use the cputime operations for each access to these variables. The default implementation is jiffies based and the effect of this patch for architectures which use the default implementation should be neglectible. There is a second type cputime64_t which is necessary for the kernel_stat cpu statistics. The default cputime_t is 32 bit and based on HZ, this will overflow after 49.7 days. This is not enough for kernel_stat (ihmo not enough for a processes too), so it is necessary to have a 64 bit type. The third thing that gets introduced by this patch is an additional field for the /proc/stat interface: cpu steal time. An architecture can account cpu steal time by calls to the account_stealtime function. The cpu which backs a virtual processor doesn't spent all of its time for the virtual cpu. To get meaningful cpu usage numbers this involuntary wait time needs to be accounted and exported to user space. From: Hugh Dickins The p->signal check in account_system_time is insufficient. If the timer interrupt hits near the end of exit_notify, after EXIT_ZOMBIE has been set, another cpu may release_task (NULLifying p->signal) in between account_system_time's check and check_rlimit's dereference. Nor should account_it_prof risk send_sig. But surely account_user_time is safe? Signed-off-by: Hugh Dickins Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel_stat.h | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) (limited to 'include/linux/kernel_stat.h') diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h index 4594ccc4a7c1..dba27749b428 100644 --- a/include/linux/kernel_stat.h +++ b/include/linux/kernel_stat.h @@ -6,6 +6,7 @@ #include #include #include +#include /* * 'kernel_stat.h' contains the definitions needed for doing @@ -14,13 +15,14 @@ */ struct cpu_usage_stat { - u64 user; - u64 nice; - u64 system; - u64 softirq; - u64 irq; - u64 idle; - u64 iowait; + cputime64_t user; + cputime64_t nice; + cputime64_t system; + cputime64_t softirq; + cputime64_t irq; + cputime64_t idle; + cputime64_t iowait; + cputime64_t steal; }; struct kernel_stat { @@ -50,4 +52,8 @@ static inline int kstat_irqs(int irq) return sum; } +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(struct task_struct *, cputime_t); + #endif /* _LINUX_KERNEL_STAT_H */ -- cgit v1.2.3