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If we want to stop the tick further idle, we need to be able to account the cputime without using the tick. Virtual based cputime accounting solves that problem by hooking into kernel/user boundaries. However implementing CONFIG_VIRT_CPU_ACCOUNTING require low level hooks and involves more overhead. But we already have a generic context tracking subsystem that is required for RCU needs by archs which plan to shut down the tick outside idle. This patch implements a generic virtual based cputime accounting that relies on these generic kernel/user hooks. There are some upsides of doing this: - This requires no arch code to implement CONFIG_VIRT_CPU_ACCOUNTING if context tracking is already built (already necessary for RCU in full tickless mode). - We can rely on the generic context tracking subsystem to dynamically (de)activate the hooks, so that we can switch anytime between virtual and tick based accounting. This way we don't have the overhead of the virtual accounting when the tick is running periodically. And one downside: - There is probably more overhead than a native virtual based cputime accounting. But this relies on hooks that are already set anyway. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
236 lines
5.3 KiB
C
236 lines
5.3 KiB
C
/*
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* Definitions for measuring cputime on powerpc machines.
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*
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* Copyright (C) 2006 Paul Mackerras, IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* If we have CONFIG_VIRT_CPU_ACCOUNTING_NATIVE, we measure cpu time in
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* the same units as the timebase. Otherwise we measure cpu time
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* in jiffies using the generic definitions.
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*/
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#ifndef __POWERPC_CPUTIME_H
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#define __POWERPC_CPUTIME_H
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#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
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#include <asm-generic/cputime.h>
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#ifdef __KERNEL__
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static inline void setup_cputime_one_jiffy(void) { }
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#endif
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#else
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#include <linux/types.h>
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#include <linux/time.h>
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#include <asm/div64.h>
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#include <asm/time.h>
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#include <asm/param.h>
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typedef u64 __nocast cputime_t;
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typedef u64 __nocast cputime64_t;
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#ifdef __KERNEL__
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/*
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* One jiffy in timebase units computed during initialization
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*/
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extern cputime_t cputime_one_jiffy;
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/*
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* Convert cputime <-> jiffies
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*/
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extern u64 __cputime_jiffies_factor;
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DECLARE_PER_CPU(unsigned long, cputime_last_delta);
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DECLARE_PER_CPU(unsigned long, cputime_scaled_last_delta);
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static inline unsigned long cputime_to_jiffies(const cputime_t ct)
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{
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return mulhdu((__force u64) ct, __cputime_jiffies_factor);
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}
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/* Estimate the scaled cputime by scaling the real cputime based on
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* the last scaled to real ratio */
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static inline cputime_t cputime_to_scaled(const cputime_t ct)
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{
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if (cpu_has_feature(CPU_FTR_SPURR) &&
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__get_cpu_var(cputime_last_delta))
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return (__force u64) ct *
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__get_cpu_var(cputime_scaled_last_delta) /
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__get_cpu_var(cputime_last_delta);
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return ct;
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}
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static inline cputime_t jiffies_to_cputime(const unsigned long jif)
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{
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u64 ct;
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unsigned long sec;
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/* have to be a little careful about overflow */
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ct = jif % HZ;
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sec = jif / HZ;
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if (ct) {
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ct *= tb_ticks_per_sec;
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do_div(ct, HZ);
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}
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if (sec)
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ct += (cputime_t) sec * tb_ticks_per_sec;
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return (__force cputime_t) ct;
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}
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static inline void setup_cputime_one_jiffy(void)
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{
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cputime_one_jiffy = jiffies_to_cputime(1);
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}
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static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
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{
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u64 ct;
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u64 sec;
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/* have to be a little careful about overflow */
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ct = jif % HZ;
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sec = jif / HZ;
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if (ct) {
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ct *= tb_ticks_per_sec;
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do_div(ct, HZ);
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}
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if (sec)
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ct += (u64) sec * tb_ticks_per_sec;
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return (__force cputime64_t) ct;
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}
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static inline u64 cputime64_to_jiffies64(const cputime_t ct)
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{
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return mulhdu((__force u64) ct, __cputime_jiffies_factor);
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}
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/*
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* Convert cputime <-> microseconds
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*/
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extern u64 __cputime_usec_factor;
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static inline unsigned long cputime_to_usecs(const cputime_t ct)
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{
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return mulhdu((__force u64) ct, __cputime_usec_factor);
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}
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static inline cputime_t usecs_to_cputime(const unsigned long us)
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{
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u64 ct;
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unsigned long sec;
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/* have to be a little careful about overflow */
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ct = us % 1000000;
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sec = us / 1000000;
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if (ct) {
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ct *= tb_ticks_per_sec;
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do_div(ct, 1000000);
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}
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if (sec)
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ct += (cputime_t) sec * tb_ticks_per_sec;
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return (__force cputime_t) ct;
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}
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#define usecs_to_cputime64(us) usecs_to_cputime(us)
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/*
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* Convert cputime <-> seconds
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*/
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extern u64 __cputime_sec_factor;
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static inline unsigned long cputime_to_secs(const cputime_t ct)
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{
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return mulhdu((__force u64) ct, __cputime_sec_factor);
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}
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static inline cputime_t secs_to_cputime(const unsigned long sec)
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{
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return (__force cputime_t)((u64) sec * tb_ticks_per_sec);
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}
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/*
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* Convert cputime <-> timespec
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*/
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static inline void cputime_to_timespec(const cputime_t ct, struct timespec *p)
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{
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u64 x = (__force u64) ct;
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unsigned int frac;
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frac = do_div(x, tb_ticks_per_sec);
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p->tv_sec = x;
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x = (u64) frac * 1000000000;
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do_div(x, tb_ticks_per_sec);
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p->tv_nsec = x;
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}
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static inline cputime_t timespec_to_cputime(const struct timespec *p)
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{
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u64 ct;
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ct = (u64) p->tv_nsec * tb_ticks_per_sec;
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do_div(ct, 1000000000);
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return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
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}
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/*
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* Convert cputime <-> timeval
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*/
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static inline void cputime_to_timeval(const cputime_t ct, struct timeval *p)
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{
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u64 x = (__force u64) ct;
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unsigned int frac;
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frac = do_div(x, tb_ticks_per_sec);
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p->tv_sec = x;
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x = (u64) frac * 1000000;
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do_div(x, tb_ticks_per_sec);
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p->tv_usec = x;
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}
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static inline cputime_t timeval_to_cputime(const struct timeval *p)
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{
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u64 ct;
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ct = (u64) p->tv_usec * tb_ticks_per_sec;
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do_div(ct, 1000000);
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return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
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}
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/*
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* Convert cputime <-> clock_t (units of 1/USER_HZ seconds)
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*/
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extern u64 __cputime_clockt_factor;
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static inline unsigned long cputime_to_clock_t(const cputime_t ct)
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{
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return mulhdu((__force u64) ct, __cputime_clockt_factor);
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}
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static inline cputime_t clock_t_to_cputime(const unsigned long clk)
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{
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u64 ct;
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unsigned long sec;
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/* have to be a little careful about overflow */
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ct = clk % USER_HZ;
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sec = clk / USER_HZ;
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if (ct) {
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ct *= tb_ticks_per_sec;
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do_div(ct, USER_HZ);
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}
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if (sec)
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ct += (u64) sec * tb_ticks_per_sec;
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return (__force cputime_t) ct;
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}
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#define cputime64_to_clock_t(ct) cputime_to_clock_t((cputime_t)(ct))
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static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
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#endif /* __KERNEL__ */
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#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
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#endif /* __POWERPC_CPUTIME_H */
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