Re: [PATCH 11/11] powerpc/smp: Provide an ability to disable coregroup

[Michael Ellerman]

Srikar Dronamraju  writes:
> If user wants to enable coregroup sched_domain then they can boot with
> kernel parameter "coregroup_support=on"

Why would they want to do that?

Adding options like this increases our test matrix by 2x (though in
reality the non-default case will never be tested).

cheers

Re: [PATCH 11/11] powerpc/smp: Provide an ability to disable coregroup

[Gautham R Shenoy]

On Tue, Jul 14, 2020 at 10:06:24AM +0530, Srikar Dronamraju wrote:
> If user wants to enable coregroup sched_domain then they can boot with
> kernel parameter "coregroup_support=on"
> 
> Cc: linuxppc-dev 
> Cc: Michael Ellerman 
> Cc: Nick Piggin 
> Cc: Oliver OHalloran 
> Cc: Nathan Lynch 
> Cc: Michael Neuling 
> Cc: Anton Blanchard 
> Cc: Gautham R Shenoy 
> Cc: Vaidyanathan Srinivasan 
> Signed-off-by: Srikar Dronamraju 


We need this documented in the
Documentation/admin-guide/kernel-parameters.txt

Other than that, the patch looks good to me.
Reviewed-by: Gautham R. Shenoy 

> ---
>  arch/powerpc/kernel/smp.c | 19 ++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index bb25c13bbb79..c43909e6e8e9 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -118,6 +118,23 @@ struct smp_ops_t *smp_ops;
>  volatile unsigned int cpu_callin_map[NR_CPUS];
> 
>  int smt_enabled_at_boot = 1;
> +int coregroup_support;
> +
> +static int __init early_coregroup(char *p)
> +{
> + if (!p)
> + return 0;
> +
> + if (strstr(p, "on"))
> + coregroup_support = 1;
> +
> + if (strstr(p, "1"))
> + coregroup_support = 1;
> +
> + return 0;
> +}
> +
> +early_param("coregroup_support", early_coregroup);
> 
>  /*
>   * Returns 1 if the specified cpu should be brought up during boot.
> @@ -878,7 +895,7 @@ static struct cpumask *cpu_coregroup_mask(int cpu)
> 
>  static bool has_coregroup_support(void)
>  {
> - return coregroup_enabled;
> + return coregroup_enabled && coregroup_support;
>  }
> 
>  static const struct cpumask *cpu_mc_mask(int cpu)
> -- 
> 2.17.1
> 

[PATCH 11/11] powerpc/smp: Provide an ability to disable coregroup

[Srikar Dronamraju]

If user wants to enable coregroup sched_domain then they can boot with
kernel parameter "coregroup_support=on"

Cc: linuxppc-dev 
Cc: Michael Ellerman 
Cc: Nick Piggin 
Cc: Oliver OHalloran 
Cc: Nathan Lynch 
Cc: Michael Neuling 
Cc: Anton Blanchard 
Cc: Gautham R Shenoy 
Cc: Vaidyanathan Srinivasan 
Signed-off-by: Srikar Dronamraju 
---
 arch/powerpc/kernel/smp.c | 19 ++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index bb25c13bbb79..c43909e6e8e9 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -118,6 +118,23 @@ struct smp_ops_t *smp_ops;
 volatile unsigned int cpu_callin_map[NR_CPUS];
 
 int smt_enabled_at_boot = 1;
+int coregroup_support;
+
+static int __init early_coregroup(char *p)
+{
+   if (!p)
+   return 0;
+
+   if (strstr(p, "on"))
+   coregroup_support = 1;
+
+   if (strstr(p, "1"))
+   coregroup_support = 1;
+
+   return 0;
+}
+
+early_param("coregroup_support", early_coregroup);
 
 /*
  * Returns 1 if the specified cpu should be brought up during boot.
@@ -878,7 +895,7 @@ static struct cpumask *cpu_coregroup_mask(int cpu)
 
 static bool has_coregroup_support(void)
 {
-   return coregroup_enabled;
+   return coregroup_enabled && coregroup_support;
 }
 
 static const struct cpumask *cpu_mc_mask(int cpu)
-- 
2.17.1