Re: [PATCH] Use boot based time for process start time and boot time in /proc

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 11 May 2007 10:45:31 +0200
Tomas Janousek <tjanouse@redhat.com> wrote:

> Hello,
> 
> On Thu, May 10, 2007 at 04:40:47PM -0700, Andrew Morton wrote:
> > Tomas Janousek <tjanouse@redhat.com> wrote:
> > > @@ -445,12 +445,14 @@ static int show_stat(struct seq_file *p, void *v)
> > >  	unsigned long jif;
> > >  	cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
> > >  	u64 sum = 0;
> > > +	struct timespec boottime;
> > >  
> > >  	user = nice = system = idle = iowait =
> > >  		irq = softirq = steal = cputime64_zero;
> > > -	jif = - wall_to_monotonic.tv_sec;
> > > -	if (wall_to_monotonic.tv_nsec)
> > > -		--jif;
> > > +	getboottime(&boottime);
> > > +	jif = boottime.tv_sec;
> > > +	if (boottime.tv_nsec)
> > > +		++jif;
> > >
> > 
> > Is the switch from --jif to ++jif a functional change?  If so, how come?
> 
> Yes, I'm afraid it was.
> 
> -----------------------
> From: Tomas Janousek <tjanouse@redhat.com>
> Date: Fri, 11 May 2007 10:34:55 +0200
> Subject: [PATCH] Lower the boot time to seconds, not ceil
> 
> Restores the original behaviour of boot time calculation.
> 
> Signed-off-by: Tomas Janousek <tjanouse@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Tomas Smetana <tsmetana@redhat.com>
> Cc: John Stultz <johnstul@us.ibm.com>
> ---
>  fs/proc/proc_misc.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
> index d84956c..60b6210 100644
> --- a/fs/proc/proc_misc.c
> +++ b/fs/proc/proc_misc.c
> @@ -452,8 +452,6 @@ static int show_stat(struct seq_file *p, void *v)
>  		irq = softirq = steal = cputime64_zero;
>  	getboottime(&boottime);
>  	jif = boottime.tv_sec;
> -	if (boottime.tv_nsec)
> -		++jif;
>  
>  	for_each_possible_cpu(i) {
>  		int j;

So we've gone from --jif to ++jif to no change at all.

Are you sure that this net removal of --jif is correct?