Messages in this thread | | | Date | Wed, 29 Mar 2006 21:04:15 -0800 | From | Andrew Morton <> | Subject | Re: [Patch 6/8] virtual cpu run time |
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Shailabh Nagar <nagar@watson.ibm.com> wrote: > > delayacct-virtcpu.patch > > Distinguish between "wall-clock" and "virtual" cpu run times and return > both, at per-task and per-tgid granularity. > > Some architectures adjust tsk->utime+tsk->stime to reflect the time that > the kernel wasn't scheduled in hypervised environments and this is the > "wall-clock" cpu run time. "Virtual" cpu run time, on the other hand, does > not account for the kernel being descheduled. > > This patch allows the most accurate "virtual" cpu run time, collected by > the schedstats code (now shared with delay accounting code), to be returned > to user space, in addition to the "wall-clock" cpu time that was being exported > earlier. Both these times are useful for workload management in different > situations. > > In a non-virtualized environment, or on architectures which do not adjust > tsk->utime/stime, these will effectively be the same value but at different > granularities. > > ... > > Index: linux-2.6.16/include/linux/taskstats.h > =================================================================== > --- linux-2.6.16.orig/include/linux/taskstats.h 2006-03-29 18:13:18.000000000 -0500 > +++ linux-2.6.16/include/linux/taskstats.h 2006-03-29 18:13:20.000000000 -0500 > @@ -46,8 +46,14 @@ struct taskstats { > __u64 swapin_count; > __u64 swapin_delay_total; /* swapin page fault wait*/ > > - __u64 cpu_run_total; /* cpu running time > - * no count available/provided */ > + __u64 cpu_run_real_total; /* cpu "wall-clock" running time > + * Potentially accounts for cpu > + * virtualization, on some arches > + */ > + __u64 cpu_run_virtual_total; /* cpu "virtual" running time > + * Uses time intervals as seen by > + * the kernel > + */ > }; >
Again, the reader of this struct wants to know what the atomicity rules are.
> + d->cpu_run_real_total = (tmp < (nsec_t)d->cpu_run_real_total)? 0: tmp;
lval = expr1 ? expr2 : expr3;
> + tmp = (nsec_t)d->cpu_run_virtual_total > + + (nsec_t)jiffies_to_usecs(t3) * 1000;
umm, Linux doesn't have nsec_t any more.
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