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authorMike Galbraith <efault@gmx.de>2009-09-09 09:41:37 -0400
committerIngo Molnar <mingo@elte.hu>2009-09-09 11:30:05 -0400
commit2bba22c50b06abe9fd0d23933b1e64d35b419262 (patch)
tree5ac0373fa1d18f043cb27183f9f185ceda598915 /kernel/sched_fair.c
parentb5d9d734a53e0204aab0089079cbde2a1285a38f (diff)
sched: Turn off child_runs_first
Set child_runs_first default to off. It hurts 'optimal' make -j<NR_CPUS> workloads as make jobs get preempted by child tasks, reducing parallelism. Note, this patch might make existing races in user applications more prominent than before - so breakages might be bisected to this commit. Child-runs-first is broken on SMP to begin with, and we already had it off briefly in v2.6.23 so most of the offenders ought to be fixed. Would be nice not to revert this commit but fix those apps finally ... Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1252486344.28645.18.camel@marge.simson.net> [ made the sysctl independent of CONFIG_SCHED_DEBUG, in case people want to work around broken apps. ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index e386e5dfcdae..af325a382b1b 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -48,10 +48,10 @@ unsigned int sysctl_sched_min_granularity = 4000000ULL;
48static unsigned int sched_nr_latency = 5; 48static unsigned int sched_nr_latency = 5;
49 49
50/* 50/*
51 * After fork, child runs first. (default) If set to 0 then 51 * After fork, child runs first. If set to 0 (default) then
52 * parent will (try to) run first. 52 * parent will (try to) run first.
53 */ 53 */
54const_debug unsigned int sysctl_sched_child_runs_first = 1; 54unsigned int sysctl_sched_child_runs_first __read_mostly;
55 55
56/* 56/*
57 * sys_sched_yield() compat mode 57 * sys_sched_yield() compat mode