On Mon, 2012-11-26 at 20:24 +0100, Frederic Weisbecker wrote: > 2012/11/26 Steven Rostedt <rost...@goodmis.org>: > > On Fri, 2012-11-23 at 15:21 +0100, Frederic Weisbecker wrote: > >> We have thread_group_cputime() and thread_group_times(). The naming > >> doesn't provide enough information about the difference between > >> these two APIs. > >> > >> To lower the confusion, rename thread_group_times() to > >> thread_group_cputime_adjusted(). This name better suggests that > >> it's a version of thread_group_cputime() that does some stabilization > >> on the raw cputime values. ie here: scale on top of CFS runtime > >> stats and bound lower value for monotonicity. > > > > But, thread_group_times() does not do any type of adjustment. It only > > retrieves the cpu times: > > > > void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) > > { > > struct task_cputime cputime; > > > > thread_group_cputime(p, &cputime); > > > > *ut = cputime.utime; > > *st = cputime.stime; > > } > > This is the CONFIG_VIRT_CPU_ACCOUNTING only version. It also needs > some monotonicity guard IMO but that's another issue. > But please look at the other version.
Yeah, I just noticed. That turkey juice is still having an affect on me ;-) > > > It retrieves the current times, it doesn't adjust them. > > > > I'm thinking the current name is more accurate. OK, let's take a look at the other version now: void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct signal_struct *sig = p->signal; struct task_cputime cputime; cputime_t rtime, utime, total; thread_group_cputime(p, &cputime); total = cputime.utime + cputime.stime; rtime = nsecs_to_cputime(cputime.sum_exec_runtime); if (total) utime = scale_utime(cputime.utime, rtime, total); else utime = rtime; sig->prev_utime = max(sig->prev_utime, utime); sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime); *ut = sig->prev_utime; *st = sig->prev_stime; } So this version also updates the task's signal->prev_[us]times as well. I guess I'll wait for you to explain to me more about what is going on :-) -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/