Messages in this thread | | | Date | Thu, 24 Sep 2009 20:49:10 +0100 (BST) | From | Michael Abbott <> | Subject | Re: [GIT PULL] cputime tree |
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On Thu, 24 Sep 2009, Andrew Morton wrote: > 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?
Yes indeed, all since the regression was introduced I think around about .28 (though I seem to remember having to tweak the code a little when rebasing it forward).
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