On Tue, 5 Nov 2013 23:27:52 +0100
Peter Zijlstra <[email protected]> wrote:
> On Tue, Nov 05, 2013 at 03:57:23PM +0100, Vincent Guittot wrote:
> > Your proposal looks fine for me. It's clearly better to move in one
> > place the configuration of sched_domain fields. Have you already got
> > an idea about how to let architecture override the topology?
>
> Maybe something like the below -- completely untested (my s390 compiler
> is on a machine that's currently powered off).
In principle I do not see a reason why this should not work, but there
are a few more things to take care of. E.g. struct sd_data is defined
in kernel/sched/core.c, cpu_cpu_mask as well. These need to be moved
to a header where arch/s390/kernel/smp.c can pick it up.
I do have the feeling that the sched_domain_topology should be left
where they are, or do we really want to expose more of the scheduler
internals?
> > My primary need comes from the fact that the topology configuration is
> > not the same for all cores
>
> Do expand.. the various cpu masks used in the topology list are per cpu,
> is that sufficient room to wriggle or do you need more?
>
> ---
> --- a/arch/s390/kernel/smp.c
> +++ b/arch/s390/kernel/smp.c
> @@ -1070,3 +1070,23 @@ static int __init s390_smp_init(void)
> return 0;
> }
> subsys_initcall(s390_smp_init);
> +
> +static struct sched_domain_topology_level s390_topology[] = {
> +#ifdef CONFIG_SCHED_SMT
> + { cpu_smt_mask, SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES },
> +#endif
> +#ifdef CONFIG_SCHED_MC
> + { cpu_coregroup_mask, SD_SHARE_PKG_RESOURCES },
> +#endif
> +#ifdef CONFIG_SCHED_BOOK
> + { cpu_book_mask, },
> +#endif
> + { cpu_cpu_mask, },
> + { NULL, },
> +};
> +
> +static int __init s390_sched_topology(void)
> +{
> + sched_domain_topology = s390_topology;
> +}
> +early_initcall(s390_sched_topology);
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -889,6 +889,20 @@ void free_sched_domains(cpumask_var_t do
>
> bool cpus_share_cache(int this_cpu, int that_cpu);
>
> +typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
> +
> +#define SDTL_OVERLAP 0x01
> +
> +struct sched_domain_topology_level {
> + sched_domain_mask_f mask;
> + int sd_flags;
> + int flags;
> + int numa_level;
> + struct sd_data data;
> +};
> +
> +extern struct sched_domain_topology_level *sched_domain_topology;
> +
> #else /* CONFIG_SMP */
>
> struct sched_domain_attr;
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5377,20 +5377,6 @@ enum s_alloc {
> sa_none,
> };
>
> -struct sched_domain_topology_level;
> -
> -typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
> -
> -#define SDTL_OVERLAP 0x01
> -
> -struct sched_domain_topology_level {
> - sched_domain_mask_f mask;
> - int sd_flags;
> - int flags;
> - int numa_level;
> - struct sd_data data;
> -};
> -
> /*
> * Build an iteration mask that can exclude certain CPUs from the upwards
> * domain traversal.
> @@ -5841,6 +5827,7 @@ sd_init(struct sched_domain_topology_lev
>
> return sd;
> }
> +
> /*
> * Topology list, bottom-up.
> */
> @@ -5851,14 +5838,11 @@ static struct sched_domain_topology_leve
> #ifdef CONFIG_SCHED_MC
> { cpu_coregroup_mask, SD_SHARE_PKG_RESOURCES },
> #endif
> -#ifdef CONFIG_SCHED_BOOK
> - { cpu_book_mask, },
> -#endif
> { cpu_cpu_mask, },
> { NULL, },
> };
>
> -static struct sched_domain_topology_level *sched_domain_topology =
> default_topology;
> +struct sched_domain_topology_level *sched_domain_topology = default_topology;
>
> #define for_each_sd_topology(tl) \
> for (tl = sched_domain_topology; tl->mask; tl++)
>
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
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