Hi Wanpeng, On Sun, Dec 08, 2013 at 02:14:50PM +0800, Wanpeng Li wrote: > commit 04bb2f947 (sched/numa: Adjust scan rate in task_numa_placement) > calculate > period_slot which should be used as base value of scan rate increase if remote > access dominate. However, current codes forget to use it, this patch fix it. > > Signed-off-by: Wanpeng Li <liw...@linux.vnet.ibm.com> > --- > kernel/sched/fair.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 7073c76..b077f1b3 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -1358,7 +1358,7 @@ static void update_task_scan_period(struct task_struct > *p, > */ > period_slot = DIV_ROUND_UP(diff, NUMA_PERIOD_SLOTS); > ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + > shared)); > - diff = (diff * ratio) / NUMA_PERIOD_SLOTS; > + diff = (period_slot * ratio) / NUMA_PERIOD_SLOTS; > } > > p->numa_scan_period = clamp(p->numa_scan_period + diff,
It seems to me that the original code is correct, because the mathematical meaning of this hunk is clear: diff = (diff calculated by local-remote ratio) * (private-shared ratio) If you use period_slot here, diff always becomes less then 1/10 finally by the second ratio multiplication (because we divide by NUMA_PERIOD_SLOTS twice), and I don't see the justification. And if my idea is correct, we don't have to recalculate period_slot when we multiply private-shared ratio. So we can remove that line. Thanks, Naoya Horiguchi -- 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/
