Re: [patch RT 3/7] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL
On Wed, 2012-07-11 at 22:05 +, Thomas Gleixner wrote:
> plain text document attachment
> (disable-rt_group_sched-in-preempt_rt_full.patch)
> Strange CPU stalls have been observed in RT when RT_GROUP_SCHED
> was configured.
>
> Disable it for now.
>
> Signed-off-by: Carsten Emde
> Signed-off-by: Thomas Gleixner
>
> ---
> init/Kconfig |1 +
> 1 file changed, 1 insertion(+)
>
> Index: linux-3.4.4-rt13-64+/init/Kconfig
> ===
> --- linux-3.4.4-rt13-64+.orig/init/Kconfig
> +++ linux-3.4.4-rt13-64+/init/Kconfig
> @@ -746,6 +746,7 @@ config RT_GROUP_SCHED
> bool "Group scheduling for SCHED_RR/FIFO"
> depends on EXPERIMENTAL
> depends on CGROUP_SCHED
> + depends on !PREEMPT_RT_FULL
> default n
> help
> This feature lets you explicitly allocate real CPU bandwidth
>
>
>
>
>
I turn the thing off because it doesn't make any sense to me for -rt,
and because it's busted. The below works around isolation bustage I
encountered. Peter didn't like it (what's to like?) but it saves the
day, so shall live on in non-rt kernels until I hopefully someday see
RT_GROUP_SCHED being fed into a Bitwolf-9000 ;-)
sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled
Root task group bandwidth replentishment must service all CPUs regardless of
where it was last started.
Signed-off-by: Mike Galbraith
---
kernel/sched/rt.c | 13 +
1 file changed, 13 insertions(+)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -782,6 +782,19 @@ static int do_sched_rt_period_timer(stru
const struct cpumask *span;
span = sched_rt_period_mask();
+#ifdef CONFIG_RT_GROUP_SCHED
+ /*
+* FIXME: isolated CPUs should really leave the root task group,
+* whether they are isolcpus or were isolated via cpusets, lest
+* the timer run on a CPU which does not service all runqueues,
+* potentially leaving other CPUs indefinitely throttled. If
+* isolation is really required, the user will turn the throttle
+* off to kill the perturbations it causes anyway. Meanwhile,
+* this maintains functionallity for boot and/or troubleshooting.
+*/
+ if (rt_b == _task_group.rt_bandwidth)
+ span = cpu_online_mask;
+#endif
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
--
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[patch RT 3/7] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL
Strange CPU stalls have been observed in RT when RT_GROUP_SCHED was configured. Disable it for now. Signed-off-by: Carsten Emde Signed-off-by: Thomas Gleixner --- init/Kconfig |1 + 1 file changed, 1 insertion(+) Index: linux-3.4.4-rt13-64+/init/Kconfig === --- linux-3.4.4-rt13-64+.orig/init/Kconfig +++ linux-3.4.4-rt13-64+/init/Kconfig @@ -746,6 +746,7 @@ config RT_GROUP_SCHED bool "Group scheduling for SCHED_RR/FIFO" depends on EXPERIMENTAL depends on CGROUP_SCHED + depends on !PREEMPT_RT_FULL default n help This feature lets you explicitly allocate real CPU bandwidth -- 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/
[patch RT 3/7] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL
Strange CPU stalls have been observed in RT when RT_GROUP_SCHED was configured. Disable it for now. Signed-off-by: Carsten Emde c.e...@osadl.org Signed-off-by: Thomas Gleixner t...@linutronix.de --- init/Kconfig |1 + 1 file changed, 1 insertion(+) Index: linux-3.4.4-rt13-64+/init/Kconfig === --- linux-3.4.4-rt13-64+.orig/init/Kconfig +++ linux-3.4.4-rt13-64+/init/Kconfig @@ -746,6 +746,7 @@ config RT_GROUP_SCHED bool Group scheduling for SCHED_RR/FIFO depends on EXPERIMENTAL depends on CGROUP_SCHED + depends on !PREEMPT_RT_FULL default n help This feature lets you explicitly allocate real CPU bandwidth -- 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/
Re: [patch RT 3/7] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL
On Wed, 2012-07-11 at 22:05 +, Thomas Gleixner wrote:
plain text document attachment
(disable-rt_group_sched-in-preempt_rt_full.patch)
Strange CPU stalls have been observed in RT when RT_GROUP_SCHED
was configured.
Disable it for now.
Signed-off-by: Carsten Emde c.e...@osadl.org
Signed-off-by: Thomas Gleixner t...@linutronix.de
---
init/Kconfig |1 +
1 file changed, 1 insertion(+)
Index: linux-3.4.4-rt13-64+/init/Kconfig
===
--- linux-3.4.4-rt13-64+.orig/init/Kconfig
+++ linux-3.4.4-rt13-64+/init/Kconfig
@@ -746,6 +746,7 @@ config RT_GROUP_SCHED
bool Group scheduling for SCHED_RR/FIFO
depends on EXPERIMENTAL
depends on CGROUP_SCHED
+ depends on !PREEMPT_RT_FULL
default n
help
This feature lets you explicitly allocate real CPU bandwidth
I turn the thing off because it doesn't make any sense to me for -rt,
and because it's busted. The below works around isolation bustage I
encountered. Peter didn't like it (what's to like?) but it saves the
day, so shall live on in non-rt kernels until I hopefully someday see
RT_GROUP_SCHED being fed into a Bitwolf-9000 ;-)
sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled
Root task group bandwidth replentishment must service all CPUs regardless of
where it was last started.
Signed-off-by: Mike Galbraith efa...@gmx.de
---
kernel/sched/rt.c | 13 +
1 file changed, 13 insertions(+)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -782,6 +782,19 @@ static int do_sched_rt_period_timer(stru
const struct cpumask *span;
span = sched_rt_period_mask();
+#ifdef CONFIG_RT_GROUP_SCHED
+ /*
+* FIXME: isolated CPUs should really leave the root task group,
+* whether they are isolcpus or were isolated via cpusets, lest
+* the timer run on a CPU which does not service all runqueues,
+* potentially leaving other CPUs indefinitely throttled. If
+* isolation is really required, the user will turn the throttle
+* off to kill the perturbations it causes anyway. Meanwhile,
+* this maintains functionallity for boot and/or troubleshooting.
+*/
+ if (rt_b == root_task_group.rt_bandwidth)
+ span = cpu_online_mask;
+#endif
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
--
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