Messages in this thread | | | Date | Mon, 23 Apr 2012 17:37:07 +0200 | From | Juri Lelli <> | Subject | Re: [PATCH 05/16] sched: SCHED_DEADLINE policy implementation. |
| |
On 04/23/2012 05:15 PM, Peter Zijlstra wrote: > On Fri, 2012-04-06 at 09:14 +0200, Juri Lelli wrote: >> +static >> +int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se) >> +{ >> + int dmiss = dl_time_before(dl_se->deadline, rq->clock); >> + int rorun = dl_se->runtime<= 0; >> + >> + if (!rorun&& !dmiss) >> + return 0; >> + >> + /* >> + * If we are beyond our current deadline and we are still >> + * executing, then we have already used some of the runtime of >> + * the next instance. Thus, if we do not account that, we are >> + * stealing bandwidth from the system at each deadline miss! >> + */ >> + if (dmiss) { >> + dl_se->runtime = rorun ? dl_se->runtime : 0; >> + dl_se->runtime -= rq->clock - dl_se->deadline; >> + } > > So ideally this can't happen, but since we already leak time from the > system through means of hardirq / kstop / context-switch-overhead / > clock-jitter etc.. we avoid the error accumulating? >
Yep, seems fair :-).
>> + >> + return 1; >> +} > >
Thanks,
- Juri
| |