On 04/03/2015 01:42 PM, Frederic Weisbecker wrote:
On Fri, Apr 03, 2015 at 12:24:08PM -0400, cmetc...@ezchip.com wrote:
From: Chris Metcalf <cmetc...@ezchip.com>

It's not clear that nohz_full is useful without isolcpus also
set, since otherwise the scheduler has to run periodically to
try to determine whether to steal work from other cores.

Signed-off-by: Chris Metcalf <cmetc...@ezchip.com>
I think Rick has a similar patch.

I didn't see anything relevant in linux-next, though I did see cpu_isolated_map
made into a public symbol in a recent commit by Rik.

Rik, what's the change you're proposing that's similar to this one? Thanks!

---
I am puzzled why this has not been done before, so I suspect
there is some argument against it that I am missing, but I
wasn't able to turn anything up by searching LKML.

  kernel/sched/core.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f0f831e8a345..275f12c608f2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6836,6 +6836,7 @@ static int init_sched_domains(const struct cpumask 
*cpu_map)
        doms_cur = alloc_sched_domains(ndoms_cur);
        if (!doms_cur)
                doms_cur = &fallback_doms;
+       tick_nohz_full_set_cpus(cpu_isolated_map);
        cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
        err = build_sched_domains(doms_cur[0], NULL);
        register_sched_domain_sysctl();
--
2.1.2


--
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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