Messages in this thread | | | Subject | Re: Fix bug: Scheduler's idle-load-balancer not running in first 5 mins after bootup | From | Mike Galbraith <> | Date | Tue, 31 Jan 2012 04:49:11 +0100 |
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On Mon, 2012-01-30 at 10:14 -0800, Diwakar Tundlam wrote: > We ran into this at Nvidia. QA filed a bug saying coremark_4pthreads scores lower (as if running on 3 cores) when run shortly after bootup. But later its score increases to expected values on 4 cores. > > This patch is relevant to linux-2.6.39 but I noticed this fix is not made in linux-3.0, 3.1, 3.2 or 3.3 also. > > Please see commit log for more details of the problem and fix. > > Thanks, > Diwakar. > Tegra Android Kernel SW Engg. > NVIDIA. > Santa Clara, CA > > commit d04d7ef0e3f8c70bd6cd5abb2abc0236aa8d1f7c > Author: Diwakar Tundlam <dtundlam@nvidia.com> > Date: Wed Jan 18 18:58:57 2012 -0800 > > scheduler: domain: init next_balance in nohz_idle_balancer with jiffies > > The next_balance parameter of nohz_idle_balancer should be initialized > to jiffies since jiffies itself is initialized to 300 seconds shy of > overflow. Otherwise, nohz_idle_balancer does not run for the first 5 > mins after bootup. > > Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com> > Reviewed-by: Aleksandr Frid <afrid@nvidia.com> > Reviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com> > Reviewed-by: Satya Popuri <spopuri@nvidia.com> > > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c index c5b09f7..506c5da 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -8288,6 +8288,7 @@ void __init sched_init(void) > atomic_set(&nohz.load_balancer, nr_cpu_ids); > atomic_set(&nohz.first_pick_cpu, nr_cpu_ids); > atomic_set(&nohz.second_pick_cpu, nr_cpu_ids); > + nohz.next_balance = jiffies; > #endif > /* May be allocated at isolcpus cmdline parse time */ > if (cpu_isolated_map == NULL)
Shouldn't that really be INITIAL_JIFFIES + HZ?
-Mike
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