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SubjectRe: [GIT PULL] cputime tree
On Thu, 24 Sep 2009 13:31:36 +0200 Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> Hi Linus,
>
> with git commit 79741dd "idle cputime accounting" the semantic
> of the stime field of the idle processes has changed. It used to
> contain the amount of time the idle process has been scheduled.
> Since git commit 79741dd is contains the cpu time spent in the
> system by the idle process.
>
> This change broke the output of second field of /proc/uptime. On
> systems without VIRT_CPU_ACCOUNTING the field is always zero.
> The legacy output of the field is the amount of time the idle
> process has been scheduled on cpu #0. It is good enough to
> calculate the load on an uni-processor system, it is useless
> on a multi-processor. To restore the legacy behaviour and give
> meaning to the multi-processor case the best we could come up
> with is to add the idle time over all cpus. That fixes uni-
> processors systems and gives a defined semantic on smp.
>
> So please pull from 'cputime' branch of
>
> git://git390.marist.edu/pub/scm/linux-2.6.git cputime
>
> to receive the following updates:
>
> Michael Abbott (1):
> Fix idle time field in /proc/uptime
>
> fs/proc/uptime.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
> index 0c10a0b..766b1d4 100644
> --- a/fs/proc/uptime.c
> +++ b/fs/proc/uptime.c
> @@ -4,13 +4,18 @@
> #include <linux/sched.h>
> #include <linux/seq_file.h>
> #include <linux/time.h>
> +#include <linux/kernel_stat.h>
> #include <asm/cputime.h>
>
> static int uptime_proc_show(struct seq_file *m, void *v)
> {
> struct timespec uptime;
> struct timespec idle;
> - cputime_t idletime = cputime_add(init_task.utime, init_task.stime);
> + int i;
> + cputime_t idletime = cputime_zero;
> +
> + for_each_possible_cpu(i)
> + idletime = cputime64_add(idletime, kstat_cpu(i).cpustat.idle);
>
> do_posix_clock_monotonic_gettime(&uptime);
> monotonic_to_bootbased(&uptime);

This is a regression fix, iirc? One which is applicable for several 2.6.x
kernel versions?



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