user/sven/linux.git/include/asm-generic/cputime.h, branch v3.0

time: Add nsecs_to_cputime64 interface for asm-generic

2011-01-26T11:33:20Z

Add nsecs_to_cputime64 interface. This is used in following patches that updates cpu irq stat based on ns granularity info in IRQ_TIME_ACCOUNTING. Tested-by: Shaun Ruffell Signed-off-by: Venkatesh Pallipadi Signed-off-by: Peter Zijlstra LKML-Reference: <1292980144-28796-3-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar

taskstats: use real microsecond granularity for CPU times

2010-10-28T01:03:17Z

The taskstats interface uses microsecond granularity for the user and system time values. The conversion from cputime to the taskstats values uses the cputime_to_msecs primitive which effectively limits the granularity to milliseconds. Add the cputime_to_usecs primitive for architectures that have better, more precise CPU time values. Remove cputime_to_msecs primitive because there are no more users left. Signed-off-by: Michael Holzheu Acked-by: Balbir Singh Cc: Luck Tony Cc: Shailabh Nagar Cc: Martin Schwidefsky Cc: Oleg Nesterov Cc: Benjamin Herrenschmidt Cc: Heiko Carstens Cc: Thomas Gleixner Cc: Shailabh Nagar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cputime: Optimize jiffies_to_cputime(1)

2009-08-03T12:48:36Z

For powerpc with CONFIG_VIRT_CPU_ACCOUNTING jiffies_to_cputime(1) is not compile time constant and run time calculations are quite expensive. To optimize we use precomputed value. For all other architectures is is preprocessor definition. Signed-off-by: Stanislaw Gruszka Acked-by: Peter Zijlstra Acked-by: Thomas Gleixner Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul Mackerras Cc: Benjamin Herrenschmidt LKML-Reference: <1248862529-6063-5-git-send-email-sgruszka@redhat.com> Signed-off-by: Ingo Molnar

taskstats scaled time cleanup

2008-02-06T18:41:00Z

This moves the ability to scale cputime into generic code. This allows us to fix the issue in kernel/timer.c (noticed by Balbir) where we could only add an unscaled value to the scaled utime/stime. This adds a cputime_to_scaled function. As before, the POWERPC version does the scaling based on the last SPURR/PURR ratio calculated. The generic and s390 (only other arch to implement asm/cputime.h) versions are both NOPs. Also moves the SPURR and PURR snapshots closer. Signed-off-by: Michael Neuling Cc: Jay Lan Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Heiko Carstens Cc: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[CPUFREQ] Remove slowdown from ondemand sampling path.

2006-06-30T05:29:47Z

Remove slowdown from ondemand sampling path. This reduces the code path length in dbs_check_cpu() by half. slowdown was not used by ondemand by default. If there are any user level tools that were using this tunable, they may report error now. Signed-off-by: Alexey Starikovskiy Signed-off-by: Venkatesh Pallipadi Signed-off-by: Dave Jones

[PATCH] posix-cpu-timers and cputime_t divisons.

2005-03-28T12:00:22Z

The posix cpu timers introduced code that will not work with an arbitrary type for cputime_t. In particular the division of two cputime_t values broke the s390 build because cputime_t is define as an unsigned long long. The first problem is the division of a cputime_t value by a number of threads. That is a cputime_t divided by an integer. The patch adds another macro cputime_div to the cputime macro regime which implements this type of division and replaces all occurences of a cputime / nthread in the posix cpu timer code. Next problem is bump_cpu_timer. This function is severly broken: 1) In the body of the first if statement a timer->it.cpu.incr.sched is used as the second argument of do_div. do_div expects an unsigned long as "base" parameter but timer->it.cpu.incr.sched is an unsigned long long. If the timer increment ever happens to be >= 2^32 the result is wrong and if the lower 32 bits are zero this even crashes with a fixed point divide exception. 2) The cputime_le(now.cpu, timer->it.cpu.expires.cpu) in the else if condition is wrong. The cputime_le() reads as "now.cpu <= timer->it.cpu.expires.cpu" and the subsequent cputime_ge() reads as "now.cpu >= timer.it.cpu.expires.cpu". That means that the two values needs to be equal to make the body of the second if to have any effect. The first cputime_le should be a cputime_ge. 3) timer->it.cpu.expires.cpu and delta in the else part of the if are of type cputime_t. A division of two cputime_t values is undefined (think of cputime_t as e.g. a struct timespec, that just doesn't work). We could add a primitive for this type of division but we'd end up with a 64 bit division or something even more complicated. The solution for bump_cpu_timer is to use the "slow" division algorithm that does shifts and subtracts. That adds yet another cputime macro, cputime_halve to do the right shift of a cputime value. The next problem is in arm_timer. The UPDATE_CLOCK macro does the wrong thing for it_prof_expires and it_virt_expires. Expanded the macro and added the cputime magic to it_prof/it_virt. The remaining problems are rather simple, timespec_to_jiffies instead of timespec_to_cputime and several cases where cputime_eq with cputime_zero needs to be used instead of "== 0". What still worries me a bit is to use "timer->it.cpu.incr.sched == 0" as check if the timer is armed at all. It should work but its not really clean. Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] cputime: simplifiy generic cputime_to_secs/secs_to_cputime

2005-02-02T00:48:52Z

The cputime_to_secs and secs_to_cputime primitives in include/asm-generic/cputime.h can be simplified since the default cputime implementation assumes that cputime is measured in jiffies. The intermediate conversion to milliseconds is superflous. Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] cputime.h seems to assume HZ==1000

2005-01-21T05:48:16Z

There's 1000 msecs in a second. No relation to HZ, which just happens to be 1000 in some cases. Signed-off-by: Linus Torvalds

[PATCH] cputime: introduce cputime

2005-01-11T09:40:38Z

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