[PATCH] taskstats scaled time cleanup

Michael Neuling
2007-10-24T06:55:17Z

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 <mikey@neuling.org>
---
arch/powerpc/kernel/time.c | 14 +++++++-------
include/asm-generic/cputime.h | 1 +
include/asm-powerpc/cputime.h | 14 ++++++++++++++
include/asm-powerpc/paca.h | 2 --
include/asm-s390/cputime.h | 1 +
kernel/timer.c | 9 +++++----
6 files changed, 28 insertions(+), 13 deletions(-)

Index: linux-2.6-ozlabs/arch/powerpc/kernel/time.c
===================================================================
--- linux-2.6-ozlabs.orig/arch/powerpc/kernel/time.c
+++ linux-2.6-ozlabs/arch/powerpc/kernel/time.c
@@ -66,6 +66,7 @@
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#include <asm/firmware.h>
+#include <asm/cputime.h>
#ifdef CONFIG_PPC_ISERIES
#include <asm/iseries/it_lp_queue.h>
#include <asm/iseries/hv_call_xm.h>
@@ -186,6 +187,8 @@ u64 __cputime_sec_factor;
EXPORT_SYMBOL(__cputime_sec_factor);
u64 __cputime_clockt_factor;
EXPORT_SYMBOL(__cputime_clockt_factor);
+DEFINE_PER_CPU(unsigned long, cputime_last_delta);
+DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);

static void calc_cputime_factors(void)
{
@@ -232,9 +235,9 @@ void account_system_vtime(struct task_st

local_irq_save(flags);
now = read_purr();
+ nowscaled = read_spurr(now);
delta = now - get_paca()->startpurr;
get_paca()->startpurr = now;
- nowscaled = read_spurr(now);
deltascaled = nowscaled - get_paca()->startspurr;
get_paca()->startspurr = nowscaled;
if (!in_interrupt()) {
@@ -247,9 +250,9 @@ void account_system_vtime(struct task_st
get_paca()->system_time = 0;
}
account_system_time(tsk, 0, delta);
- get_paca()->purrdelta = delta;
+ per_cpu(cputime_last_delta, smp_processor_id()) = delta;
account_system_time_scaled(tsk, deltascaled);
- get_paca()->spurrdelta = deltascaled;
+ per_cpu(cputime_scaled_last_delta, smp_processor_id()) = deltascaled;
local_irq_restore(flags);
}

@@ -267,10 +270,7 @@ void account_process_vtime(struct task_s
get_paca()->user_time = 0;
account_user_time(tsk, utime);

- /* Estimate the scaled utime by scaling the real utime based
- * on the last spurr to purr ratio */
- utimescaled = utime * get_paca()->spurrdelta / get_paca()->purrdelta;
- get_paca()->spurrdelta = get_paca()->purrdelta = 0;
+ utimescaled = cputime_to_scaled(utime);
account_user_time_scaled(tsk, utimescaled);
}

Index: linux-2.6-ozlabs/include/asm-generic/cputime.h
===================================================================
--- linux-2.6-ozlabs.orig/include/asm-generic/cputime.h
+++ linux-2.6-ozlabs/include/asm-generic/cputime.h
@@ -18,6 +18,7 @@ typedef unsigned long cputime_t;
#define cputime_lt(__a, __b) ((__a) < (__b))
#define cputime_le(__a, __b) ((__a) <= (__b))
#define cputime_to_jiffies(__ct) (__ct)
+#define cputime_to_scaled(__ct) (__ct)
#define jiffies_to_cputime(__hz) (__hz)

typedef u64 cputime64_t;
Index: linux-2.6-ozlabs/include/asm-powerpc/cputime.h
===================================================================
--- linux-2.6-ozlabs.orig/include/asm-powerpc/cputime.h
+++ linux-2.6-ozlabs/include/asm-powerpc/cputime.h
@@ -52,12 +52,26 @@ typedef u64 cputime64_t;
* Convert cputime <-> jiffies
*/
extern u64 __cputime_jiffies_factor;
+DECLARE_PER_CPU(unsigned long, cputime_last_delta);
+DECLARE_PER_CPU(unsigned long, cputime_scaled_last_delta);

static inline unsigned long cputime_to_jiffies(const cputime_t ct)
{
return mulhdu(ct, __cputime_jiffies_factor);
}

+/* Estimate the scaled cputime by scaling the real cputime based on
+ * the last scaled to real ratio */
+static inline cputime_t cputime_to_scaled(const cputime_t ct)
+{
+ if (cpu_has_feature(CPU_FTR_SPURR) &&
+ per_cpu(cputime_last_delta, smp_processor_id()))
+ return ct *
+ per_cpu(cputime_scaled_last_delta, smp_processor_id())/
+ per_cpu(cputime_last_delta, smp_processor_id());
+ return ct;
+}
+
static inline cputime_t jiffies_to_cputime(const unsigned long jif)
{
cputime_t ct;
Index: linux-2.6-ozlabs/include/asm-powerpc/paca.h
===================================================================
--- linux-2.6-ozlabs.orig/include/asm-powerpc/paca.h
+++ linux-2.6-ozlabs/include/asm-powerpc/paca.h
@@ -115,8 +115,6 @@ struct paca_struct {
u64 system_time; /* accumulated system TB ticks */
u64 startpurr; /* PURR/TB value snapshot */
u64 startspurr; /* SPURR value snapshot */
- u64 purrdelta; /* FIXME: document */
- u64 spurrdelta; /* FIXME: document */
};

extern struct paca_struct paca[];
Index: linux-2.6-ozlabs/include/asm-s390/cputime.h
===================================================================
--- linux-2.6-ozlabs.orig/include/asm-s390/cputime.h
+++ linux-2.6-ozlabs/include/asm-s390/cputime.h
@@ -54,6 +54,7 @@ __div(unsigned long long n, unsigned int
#define cputime_lt(__a, __b) ((__a) < (__b))
#define cputime_le(__a, __b) ((__a) <= (__b))
#define cputime_to_jiffies(__ct) (__div((__ct), 1000000 / HZ))
+#define cputime_to_scaled(__ct) (__ct)
#define jiffies_to_cputime(__hz) ((cputime_t)(__hz) * (1000000 / HZ))

#define cputime64_zero (0ULL)
Index: linux-2.6-ozlabs/kernel/timer.c
===================================================================
--- linux-2.6-ozlabs.orig/kernel/timer.c
+++ linux-2.6-ozlabs/kernel/timer.c
@@ -825,14 +825,15 @@ void update_process_times(int user_tick)
{
struct task_struct *p = current;
int cpu = smp_processor_id();
+ cputime_t one_jiffy = jiffies_to_cputime(1);

/* Note: this timer irq context must be accounted for as well. */
if (user_tick) {
- account_user_time(p, jiffies_to_cputime(1));
- account_user_time_scaled(p, jiffies_to_cputime(1));
+ account_user_time(p, one_jiffy);
+ account_user_time_scaled(p, cputime_to_scaled(one_jiffy));
} else {
- account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
- account_system_time_scaled(p, jiffies_to_cputime(1));
+ account_system_time(p, HARDIRQ_OFFSET, one_jiffy);
+ account_system_time_scaled(p, cputime_to_scaled(one_jiffy));
}
run_local_timers();
if (rcu_pending(cpu))