2020-07-21 11:40:12

by Srikar Dronamraju

Subject: [PATCH v2 04/10] powerpc/smp: Enable small core scheduling sooner

Enable small core scheduling as soon as we detect that we are in a
system that supports thread group. Doing so would avoid a redundant
check.

Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Oliver OHalloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Vaidyanathan Srinivasan <[email protected]>
Cc: Jordan Niethe <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog v1 -> v2:
powerpc/smp: Enable small core scheduling sooner
Restored the previous info msg (Jordan)
Moved big core topology fixup to fixup_topology (Gautham)

arch/powerpc/kernel/smp.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 1ce95da00cb6..72f16dc0cb26 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1370,6 +1370,16 @@ int setup_profiling_timer(unsigned int multiplier)
return 0;
}

+static void fixup_topology(void)
+{
+#ifdef CONFIG_SCHED_SMT
+ if (has_big_cores) {
+ pr_info("Big cores detected but using small core scheduling\n");
+ powerpc_topology[0].mask = smallcore_smt_mask;
+ }
+#endif
+}
+
void __init smp_cpus_done(unsigned int max_cpus)
{
/*
@@ -1383,12 +1393,7 @@ void __init smp_cpus_done(unsigned int max_cpus)

dump_numa_cpu_topology();

-#ifdef CONFIG_SCHED_SMT
- if (has_big_cores) {
- pr_info("Big cores detected but using small core scheduling\n");
- powerpc_topology[0].mask = smallcore_smt_mask;
- }
-#endif
+ fixup_topology();
set_sched_topology(powerpc_topology);
}

--
2.17.1

2020-07-22 06:00:24

by Gautham R Shenoy

Subject: Re: [PATCH v2 04/10] powerpc/smp: Enable small core scheduling sooner

Hello Srikar,

On Tue, Jul 21, 2020 at 05:08:08PM +0530, Srikar Dronamraju wrote:
> Enable small core scheduling as soon as we detect that we are in a
> system that supports thread group. Doing so would avoid a redundant
> check.

The patch looks good to me. However, I think the commit message still
reflect the v1 code where we were moving the functionality from
smp_cpus_done() to init_big_cores().

In this we are moving it to a helper function to collate all fixups to
topology.

>
> Cc: linuxppc-dev <[email protected]>
> Cc: LKML <[email protected]>
> Cc: Michael Ellerman <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Valentin Schneider <[email protected]>
> Cc: Nick Piggin <[email protected]>
> Cc: Oliver OHalloran <[email protected]>
> Cc: Nathan Lynch <[email protected]>
> Cc: Michael Neuling <[email protected]>
> Cc: Anton Blanchard <[email protected]>
> Cc: Gautham R Shenoy <[email protected]>
> Cc: Vaidyanathan Srinivasan <[email protected]>
> Cc: Jordan Niethe <[email protected]>
> Signed-off-by: Srikar Dronamraju <[email protected]>
> ---
> Changelog v1 -> v2:
> powerpc/smp: Enable small core scheduling sooner
> Restored the previous info msg (Jordan)
> Moved big core topology fixup to fixup_topology (Gautham)
>
> arch/powerpc/kernel/smp.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 1ce95da00cb6..72f16dc0cb26 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -1370,6 +1370,16 @@ int setup_profiling_timer(unsigned int multiplier)
> return 0;
> }
>
> +static void fixup_topology(void)
> +{
> +#ifdef CONFIG_SCHED_SMT
> + if (has_big_cores) {
> + pr_info("Big cores detected but using small core scheduling\n");
> + powerpc_topology[0].mask = smallcore_smt_mask;
> + }
> +#endif
> +}
> +
> void __init smp_cpus_done(unsigned int max_cpus)
> {
> /*
> @@ -1383,12 +1393,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
>
> dump_numa_cpu_topology();
>
> -#ifdef CONFIG_SCHED_SMT
> - if (has_big_cores) {
> - pr_info("Big cores detected but using small core scheduling\n");
> - powerpc_topology[0].mask = smallcore_smt_mask;
> - }
> -#endif
> + fixup_topology();
> set_sched_topology(powerpc_topology);
> }
>
> --
> 2.17.1
>

2020-07-22 07:02:21

by Srikar Dronamraju

Subject: Re: [PATCH v2 04/10] powerpc/smp: Enable small core scheduling sooner

* Gautham R Shenoy <[email protected]> [2020-07-22 11:29:25]:

> Hello Srikar,
>
> On Tue, Jul 21, 2020 at 05:08:08PM +0530, Srikar Dronamraju wrote:
> > Enable small core scheduling as soon as we detect that we are in a
> > system that supports thread group. Doing so would avoid a redundant
> > check.
>
> The patch looks good to me. However, I think the commit message still
> reflect the v1 code where we were moving the functionality from
> smp_cpus_done() to init_big_cores().
>
> In this we are moving it to a helper function to collate all fixups to
> topology.
>

Right.
Thanks for pointing , will correct this.


--
Thanks and Regards
Srikar Dronamraju