Messages in this thread Patch in this message | | | Date | Wed, 05 Mar 2014 22:38:52 +0000 | From | Dietmar Eggemann <> | Subject | Re: [RFC 6/6] sched: ARM: create a dedicated scheduler topology table |
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On 05/03/14 07:18, Vincent Guittot wrote: > Create a dedicated topology table for ARM which will create new level to > differentiate CPUs that can or not powergate independantly from others. > > The patch gives an example of how to add domain that will take advantage of > SD_SHARE_POWERDOMAIN. > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > arch/arm/kernel/topology.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c > index 0bc94b1..ae8ffbc 100644 > --- a/arch/arm/kernel/topology.c > +++ b/arch/arm/kernel/topology.c > @@ -185,6 +185,15 @@ const struct cpumask *cpu_coregroup_mask(int cpu) > return &cpu_topology[cpu].core_sibling; > } > > +/* > + * The current assumption is that we can power gate each core independently. > + * This will be superseded by DT binding once available. > + */ > +const struct cpumask *cpu_corepower_mask(int cpu) > +{ > + return &cpu_topology[cpu].thread_sibling; > +}
Although you already explained this to me in a private conversation, it's important to notice that running this set-up on a dual cluster TC2 (2 Cortex A15 - 3 Cortex A7) (no independent core power gating) we don't see the SD_SHARE_POWERDOMAIN topology flag set in the sd's on MC level because this patch-set doesn't contain the appropriate DT parsing. Like you said back then, the comment above mentions this.
> + > static void update_siblings_masks(unsigned int cpuid) > { > struct cputopo_arm *cpu_topo, *cpuid_topo = &cpu_topology[cpuid]; > @@ -266,6 +275,20 @@ void store_cpu_topology(unsigned int cpuid) > cpu_topology[cpuid].socket_id, mpidr); > } > > +static struct sched_domain_topology_level arm_topology[] = { > +#ifdef CONFIG_SCHED_MC > + { cpu_corepower_mask, SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN, SD_INIT_NAME(GMC) }, > + { cpu_coregroup_mask, SD_SHARE_PKG_RESOURCES, SD_INIT_NAME(MC) }, > +#endif > + { cpu_cpu_mask, SD_INIT_NAME(DIE) }, > + { NULL, }, > +}; > + > +static void __init set_sched_topology(void) > +{ > + sched_domain_topology = arm_topology; > +} > + > /* > * init_cpu_topology is called at boot when only one cpu is running > * which prevent simultaneous write access to cpu_topology array > @@ -289,4 +312,7 @@ void __init init_cpu_topology(void) > smp_wmb(); > > parse_dt_topology(); > + > + /* Set scheduler topology descriptor */ > + set_sched_topology(); > } >
How about the core scheduler provides an interface set_sched_topology() instead of each arch has its own __init function? Sketched out below for ARM.
-- >8 -- Subject: [PATCH] sched: set_sched_topology() as an interface of core scheduler
--- arch/arm/kernel/topology.c | 7 +------ include/linux/sched.h | 2 +- kernel/sched/core.c | 5 +++++ 3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index ae8ffbc..89d5592 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -284,11 +284,6 @@ static struct sched_domain_topology_level arm_topology[] = { { NULL, }, }; -static void __init set_sched_topology(void) -{ - sched_domain_topology = arm_topology; -} - /* * init_cpu_topology is called at boot when only one cpu is running * which prevent simultaneous write access to cpu_topology array @@ -314,5 +309,5 @@ void __init init_cpu_topology(void) parse_dt_topology(); /* Set scheduler topology descriptor */ - set_sched_topology(); + set_sched_topology(arm_topology); } diff --git a/include/linux/sched.h b/include/linux/sched.h index 8831413..fefd4e7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -998,7 +998,7 @@ struct sched_domain_topology_level { #endif }; -extern struct sched_domain_topology_level *sched_domain_topology; +extern void set_sched_topology(struct sched_domain_topology_level *tl); #ifdef CONFIG_SCHED_DEBUG # define SD_INIT_NAME(type) .name = #type diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b4fb0df..a748c92 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6105,6 +6105,11 @@ static struct sched_domain_topology_level default_topology[] = { struct sched_domain_topology_level *sched_domain_topology = default_topology; +void set_sched_topology(struct sched_domain_topology_level *tl) +{ + sched_domain_topology = tl; +} + #define for_each_sd_topology(tl) \ for (tl = sched_domain_topology; tl->mask; tl++) -- 1.8.3.2
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