diff options
| author | Mike Galbraith <efault@gmx.de> | 2009-09-09 15:41:37 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-09 17:30:05 +0200 |
| commit | 2bba22c50b06abe9fd0d23933b1e64d35b419262 (patch) | |
| tree | 5ac0373fa1d18f043cb27183f9f185ceda598915 /kernel | |
| parent | b5d9d734a53e0204aab0089079cbde2a1285a38f (diff) | |
| download | linux-2bba22c50b06abe9fd0d23933b1e64d35b419262.tar.gz linux-2bba22c50b06abe9fd0d23933b1e64d35b419262.tar.bz2 linux-2bba22c50b06abe9fd0d23933b1e64d35b419262.zip | |
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')
| -rw-r--r-- | kernel/sched_fair.c | 4 | ||||
| -rw-r--r-- | kernel/sysctl.c | 16 |
2 files changed, 10 insertions, 10 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; static unsigned int sched_nr_latency = 5; /* - * After fork, child runs first. (default) If set to 0 then + * After fork, child runs first. If set to 0 (default) then * parent will (try to) run first. */ -const_debug unsigned int sysctl_sched_child_runs_first = 1; +unsigned int sysctl_sched_child_runs_first __read_mostly; /* * sys_sched_yield() compat mode diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 6c9836ef4b47..25d6bf3383be 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -246,6 +246,14 @@ static int max_wakeup_granularity_ns = NSEC_PER_SEC; /* 1 second */ #endif static struct ctl_table kern_table[] = { + { + .ctl_name = CTL_UNNUMBERED, + .procname = "sched_child_runs_first", + .data = &sysctl_sched_child_runs_first, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, #ifdef CONFIG_SCHED_DEBUG { .ctl_name = CTL_UNNUMBERED, @@ -300,14 +308,6 @@ static struct ctl_table kern_table[] = { }, { .ctl_name = CTL_UNNUMBERED, - .procname = "sched_child_runs_first", - .data = &sysctl_sched_child_runs_first, - .maxlen = sizeof(unsigned int), - .mode = 0644, - .proc_handler = &proc_dointvec, - }, - { - .ctl_name = CTL_UNNUMBERED, .procname = "sched_features", .data = &sysctl_sched_features, .maxlen = sizeof(unsigned int), |