Hi Andreas,
> Commit d57af9b (taskstats: use real microsecond granularity for CPU
> times) renamed msecs_to_cputime to usecs_to_cputime, but failed to
> update all numbers on the way. This causes nonsensical cpu
> idle/iowait values to be displayed in /proc/stat (the only user of
> usecs_to_cputime so far).
>
> This also renames __cputime_msec_factor to __cputime_usec_factor,
> adapting its value and using it directly in cputime_to_usecs instead
> of doing two multiplications.
Thanks for finding this! I noticed the strange behaviour yesterday and
was just about to investigate.
Can I suggest we add:
Cc: <sta...@vger.kernel.org> [2.6.37+]
so it will make it back into the stable trees?
Anton
> Signed-off-by: Andreas Schwab <sch...@linux-m68k.org>
FWIW:
Acked-by: Anton Blanchard <an...@samba.org>
> ---
> arch/powerpc/include/asm/cputime.h | 6 +++---
> arch/powerpc/kernel/time.c | 10 +++++-----
> 2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/cputime.h
> b/arch/powerpc/include/asm/cputime.h index 1cf20bd..33a3580 100644
> --- a/arch/powerpc/include/asm/cputime.h
> +++ b/arch/powerpc/include/asm/cputime.h
> @@ -126,11 +126,11 @@ static inline u64 cputime64_to_jiffies64(const
> cputime_t ct) /*
> * Convert cputime <-> microseconds
> */
> -extern u64 __cputime_msec_factor;
> +extern u64 __cputime_usec_factor;
>
> static inline unsigned long cputime_to_usecs(const cputime_t ct)
> {
> - return mulhdu(ct, __cputime_msec_factor) * USEC_PER_MSEC;
> + return mulhdu(ct, __cputime_usec_factor);
> }
>
> static inline cputime_t usecs_to_cputime(const unsigned long us)
> @@ -143,7 +143,7 @@ static inline cputime_t usecs_to_cputime(const
> unsigned long us) sec = us / 1000000;
> if (ct) {
> ct *= tb_ticks_per_sec;
> - do_div(ct, 1000);
> + do_div(ct, 1000000);
> }
> if (sec)
> ct += (cputime_t) sec * tb_ticks_per_sec;
> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
> index 522bb1d..69477e5 100644
> --- a/arch/powerpc/kernel/time.c
> +++ b/arch/powerpc/kernel/time.c
> @@ -168,13 +168,13 @@ EXPORT_SYMBOL_GPL(ppc_tb_freq);
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING
> /*
> * Factors for converting from cputime_t (timebase ticks) to
> - * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
> + * jiffies, microseconds, seconds, and clock_t (1/USER_HZ seconds).
> * These are all stored as 0.64 fixed-point binary fractions.
> */
> u64 __cputime_jiffies_factor;
> EXPORT_SYMBOL(__cputime_jiffies_factor);
> -u64 __cputime_msec_factor;
> -EXPORT_SYMBOL(__cputime_msec_factor);
> +u64 __cputime_usec_factor;
> +EXPORT_SYMBOL(__cputime_usec_factor);
> u64 __cputime_sec_factor;
> EXPORT_SYMBOL(__cputime_sec_factor);
> u64 __cputime_clockt_factor;
> @@ -192,8 +192,8 @@ static void calc_cputime_factors(void)
>
> div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
> __cputime_jiffies_factor = res.result_low;
> - div128_by_32(1000, 0, tb_ticks_per_sec, &res);
> - __cputime_msec_factor = res.result_low;
> + div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
> + __cputime_usec_factor = res.result_low;
> div128_by_32(1, 0, tb_ticks_per_sec, &res);
> __cputime_sec_factor = res.result_low;
> div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
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