c6622f63db
This implements accurate task and cpu time accounting for 64-bit
powerpc kernels. Instead of accounting a whole jiffy of time to a
task on a timer interrupt because that task happened to be running at
the time, we now account time in units of timebase ticks according to
the actual time spent by the task in user mode and kernel mode. We
also count the time spent processing hardware and software interrupts
accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If
that is not set, we do tick-based approximate accounting as before.
To get this accurate information, we read either the PURR (processor
utilization of resources register) on POWER5 machines, or the timebase
on other machines on
* each entry to the kernel from usermode
* each exit to usermode
* transitions between process context, hard irq context and soft irq
context in kernel mode
* context switches.
On POWER5 systems with shared-processor logical partitioning we also
read both the PURR and the timebase at each timer interrupt and
context switch in order to determine how much time has been taken by
the hypervisor to run other partitions ("steal" time). Unfortunately,
since we need values of the PURR on both threads at the same time to
accurately calculate the steal time, and since we can only calculate
steal time on a per-core basis, the apportioning of the steal time
between idle time (time which we ceded to the hypervisor in the idle
loop) and actual stolen time is somewhat approximate at the moment.
This is all based quite heavily on what s390 does, and it uses the
generic interfaces that were added by the s390 developers,
i.e. account_system_time(), account_user_time(), etc.
This patch doesn't add any new interfaces between the kernel and
userspace, and doesn't change the units in which time is reported to
userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(),
times(), etc. Internally the various task and cpu times are stored in
timebase units, but they are converted to USER_HZ units (1/100th of a
second) when reported to userspace. Some precision is therefore lost
but there should not be any accumulating error, since the internal
accumulation is at full precision.
Signed-off-by: Paul Mackerras <paulus@samba.org>
163 lines
3.8 KiB
C
163 lines
3.8 KiB
C
/*
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* Common time prototypes and such for all ppc machines.
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*
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* Written by Cort Dougan (cort@fsmlabs.com) to merge
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* Paul Mackerras' version and mine for PReP and Pmac.
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*/
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#ifdef __KERNEL__
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#ifndef __ASM_TIME_H__
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#define __ASM_TIME_H__
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#include <linux/config.h>
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#include <linux/types.h>
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#include <linux/rtc.h>
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#include <linux/threads.h>
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#include <asm/reg.h>
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/* time.c */
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extern unsigned tb_ticks_per_jiffy;
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extern unsigned tb_to_us;
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extern unsigned tb_last_stamp;
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extern unsigned long disarm_decr[NR_CPUS];
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extern void to_tm(int tim, struct rtc_time * tm);
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extern time_t last_rtc_update;
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extern void set_dec_cpu6(unsigned int val);
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int via_calibrate_decr(void);
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/* Accessor functions for the decrementer register.
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* The 4xx doesn't even have a decrementer. I tried to use the
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* generic timer interrupt code, which seems OK, with the 4xx PIT
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* in auto-reload mode. The problem is PIT stops counting when it
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* hits zero. If it would wrap, we could use it just like a decrementer.
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*/
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static __inline__ unsigned int get_dec(void)
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{
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#if defined(CONFIG_40x)
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return (mfspr(SPRN_PIT));
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#else
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return (mfspr(SPRN_DEC));
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#endif
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}
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static __inline__ void set_dec(unsigned int val)
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{
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#if defined(CONFIG_40x)
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return; /* Have to let it auto-reload */
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#elif defined(CONFIG_8xx_CPU6)
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set_dec_cpu6(val);
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#else
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mtspr(SPRN_DEC, val);
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#endif
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}
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/* Accessor functions for the timebase (RTC on 601) registers. */
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/* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
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#ifdef CONFIG_6xx
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extern __inline__ int __attribute_pure__ __USE_RTC(void) {
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return (mfspr(SPRN_PVR)>>16) == 1;
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}
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#else
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#define __USE_RTC() 0
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#endif
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extern __inline__ unsigned long get_tbl(void) {
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unsigned long tbl;
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#if defined(CONFIG_403GCX)
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asm volatile("mfspr %0, 0x3dd" : "=r" (tbl));
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#else
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asm volatile("mftb %0" : "=r" (tbl));
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#endif
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return tbl;
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}
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extern __inline__ unsigned long get_tbu(void) {
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unsigned long tbl;
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#if defined(CONFIG_403GCX)
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asm volatile("mfspr %0, 0x3dc" : "=r" (tbl));
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#else
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asm volatile("mftbu %0" : "=r" (tbl));
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#endif
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return tbl;
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}
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extern __inline__ void set_tb(unsigned int upper, unsigned int lower)
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{
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mtspr(SPRN_TBWL, 0);
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mtspr(SPRN_TBWU, upper);
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mtspr(SPRN_TBWL, lower);
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}
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extern __inline__ unsigned long get_rtcl(void) {
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unsigned long rtcl;
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asm volatile("mfrtcl %0" : "=r" (rtcl));
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return rtcl;
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}
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extern __inline__ unsigned long get_rtcu(void)
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{
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unsigned long rtcu;
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asm volatile("mfrtcu %0" : "=r" (rtcu));
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return rtcu;
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}
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extern __inline__ unsigned get_native_tbl(void) {
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if (__USE_RTC())
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return get_rtcl();
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else
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return get_tbl();
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}
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/* On machines with RTC, this function can only be used safely
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* after the timestamp and for 1 second. It is only used by gettimeofday
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* however so it should not matter.
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*/
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extern __inline__ unsigned tb_ticks_since(unsigned tstamp) {
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if (__USE_RTC()) {
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int delta = get_rtcl() - tstamp;
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return delta<0 ? delta + 1000000000 : delta;
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} else {
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return get_tbl() - tstamp;
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}
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}
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#if 0
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extern __inline__ unsigned long get_bin_rtcl(void) {
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unsigned long rtcl, rtcu1, rtcu2;
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asm volatile("\
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1: mfrtcu %0\n\
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mfrtcl %1\n\
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mfrtcu %2\n\
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cmpw %0,%2\n\
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bne- 1b\n"
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: "=r" (rtcu1), "=r" (rtcl), "=r" (rtcu2)
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: : "cr0");
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return rtcu2*1000000000+rtcl;
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}
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extern __inline__ unsigned binary_tbl(void) {
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if (__USE_RTC())
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return get_bin_rtcl();
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else
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return get_tbl();
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}
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#endif
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/* Use mulhwu to scale processor timebase to timeval */
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/* Specifically, this computes (x * y) / 2^32. -- paulus */
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#define mulhwu(x,y) \
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({unsigned z; asm ("mulhwu %0,%1,%2" : "=r" (z) : "r" (x), "r" (y)); z;})
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unsigned mulhwu_scale_factor(unsigned, unsigned);
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#define account_process_vtime(tsk) do { } while (0)
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#define calculate_steal_time() do { } while (0)
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#define snapshot_timebases() do { } while (0)
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#endif /* __ASM_TIME_H__ */
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#endif /* __KERNEL__ */
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