From: Gautham R Shenoy <ego@linux.vnet.ibm.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Michael Neuling <mikey@neuling.org>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Oliver O'Halloran <oohall@gmail.com>,
Jordan Niethe <jniethe5@gmail.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v4 06/10] powerpc/smp: Generalize 2nd sched domain
Date: Thu, 30 Jul 2020 11:25:17 +0530 [thread overview]
Message-ID: <20200730055517.GA29623@in.ibm.com> (raw)
In-Reply-To: <20200727053230.19753-7-srikar@linux.vnet.ibm.com>
On Mon, Jul 27, 2020 at 11:02:26AM +0530, Srikar Dronamraju wrote:
> Currently "CACHE" domain happens to be the 2nd sched domain as per
> powerpc_topology. This domain will collapse if cpumask of l2-cache is
> same as SMT domain. However we could generalize this domain such that it
> could mean either be a "CACHE" domain or a "BIGCORE" domain.
>
> While setting up the "CACHE" domain, check if shared_cache is already
> set.
>
> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
> Cc: LKML <linux-kernel@vger.kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Anton Blanchard <anton@ozlabs.org>
> Cc: Oliver O'Halloran <oohall@gmail.com>
> Cc: Nathan Lynch <nathanl@linux.ibm.com>
> Cc: Michael Neuling <mikey@neuling.org>
> Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Jordan Niethe <jniethe5@gmail.com>
> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> ---
> Changelog v1 -> v2:
> Moved shared_cache topology fixup to fixup_topology (Gautham)
>
> arch/powerpc/kernel/smp.c | 48 +++++++++++++++++++++++++++------------
> 1 file changed, 34 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index d997c7411664..3c5ccf6d2b1c 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -85,6 +85,14 @@ EXPORT_PER_CPU_SYMBOL(cpu_l2_cache_map);
> EXPORT_PER_CPU_SYMBOL(cpu_core_map);
> EXPORT_SYMBOL_GPL(has_big_cores);
>
> +enum {
> +#ifdef CONFIG_SCHED_SMT
> + smt_idx,
> +#endif
> + bigcore_idx,
> + die_idx,
> +};
> +
> #define MAX_THREAD_LIST_SIZE 8
> #define THREAD_GROUP_SHARE_L1 1
> struct thread_groups {
> @@ -851,13 +859,7 @@ static int powerpc_shared_cache_flags(void)
> */
> static const struct cpumask *shared_cache_mask(int cpu)
> {
> - if (shared_caches)
> - return cpu_l2_cache_mask(cpu);
> -
> - if (has_big_cores)
> - return cpu_smallcore_mask(cpu);
> -
> - return per_cpu(cpu_sibling_map, cpu);
> + return per_cpu(cpu_l2_cache_map, cpu);
> }
>
> #ifdef CONFIG_SCHED_SMT
> @@ -867,11 +869,16 @@ static const struct cpumask *smallcore_smt_mask(int cpu)
> }
> #endif
>
> +static const struct cpumask *cpu_bigcore_mask(int cpu)
> +{
> + return per_cpu(cpu_sibling_map, cpu);
> +}
> +
> static struct sched_domain_topology_level powerpc_topology[] = {
> #ifdef CONFIG_SCHED_SMT
> { cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },
> #endif
> - { shared_cache_mask, powerpc_shared_cache_flags, SD_INIT_NAME(CACHE) },
> + { cpu_bigcore_mask, SD_INIT_NAME(BIGCORE) },
> { cpu_cpu_mask, SD_INIT_NAME(DIE) },
> { NULL, },
> };
> @@ -1311,7 +1318,6 @@ static void add_cpu_to_masks(int cpu)
> void start_secondary(void *unused)
> {
> unsigned int cpu = smp_processor_id();
> - struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask;
>
> mmgrab(&init_mm);
> current->active_mm = &init_mm;
> @@ -1337,14 +1343,20 @@ void start_secondary(void *unused)
> /* Update topology CPU masks */
> add_cpu_to_masks(cpu);
>
> - if (has_big_cores)
> - sibling_mask = cpu_smallcore_mask;
> /*
> * Check for any shared caches. Note that this must be done on a
> * per-core basis because one core in the pair might be disabled.
> */
> - if (!cpumask_equal(cpu_l2_cache_mask(cpu), sibling_mask(cpu)))
> - shared_caches = true;
> + if (!shared_caches) {
> + struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask;
> + struct cpumask *mask = cpu_l2_cache_mask(cpu);
> +
> + if (has_big_cores)
> + sibling_mask = cpu_smallcore_mask;
> +
> + if (cpumask_weight(mask) > cpumask_weight(sibling_mask(cpu)))
> + shared_caches = true;
> + }
>
> set_numa_node(numa_cpu_lookup_table[cpu]);
> set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu]));
> @@ -1375,9 +1387,17 @@ 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;
> + powerpc_topology[smt_idx].mask = smallcore_smt_mask;
> }
> #endif
> + if (shared_caches) {
> + pr_info("Using shared cache scheduler topology\n");
> + powerpc_topology[bigcore_idx].mask = shared_cache_mask;
> + powerpc_topology[bigcore_idx].sd_flags = powerpc_shared_cache_flags;
> +#ifdef CONFIG_SCHED_DEBUG
> + powerpc_topology[bigcore_idx].name = "CACHE";
> +#endif
> + }
> }
>
> void __init smp_cpus_done(unsigned int max_cpus)
> --
> 2.17.1
>
next prev parent reply other threads:[~2020-07-30 5:59 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 5:32 [PATCH v4 00/10] Coregroup support on Powerpc Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 01/10] powerpc/smp: Fix a warning under !NEED_MULTIPLE_NODES Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 02/10] powerpc/smp: Merge Power9 topology with Power topology Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 03/10] powerpc/smp: Move powerpc_topology above Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 04/10] powerpc/smp: Move topology fixups into a new function Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 05/10] powerpc/smp: Dont assume l2-cache to be superset of sibling Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 06/10] powerpc/smp: Generalize 2nd sched domain Srikar Dronamraju
2020-07-30 5:55 ` Gautham R Shenoy [this message]
2020-07-31 7:45 ` Michael Ellerman
2020-07-31 9:29 ` Srikar Dronamraju
2020-07-31 12:22 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 07/10] Powerpc/numa: Detect support for coregroup Srikar Dronamraju
2020-07-31 7:49 ` Michael Ellerman
2020-07-31 9:18 ` Srikar Dronamraju
2020-07-31 11:31 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 08/10] powerpc/smp: Allocate cpumask only after searching thread group Srikar Dronamraju
2020-07-31 7:52 ` Michael Ellerman
2020-07-31 9:49 ` Srikar Dronamraju
2020-07-31 12:14 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 09/10] Powerpc/smp: Create coregroup domain Srikar Dronamraju
2020-07-27 18:52 ` Gautham R Shenoy
2020-07-28 15:03 ` Valentin Schneider
2020-07-29 6:13 ` Srikar Dronamraju
2020-07-31 1:05 ` Valentin Schneider
2020-08-03 6:01 ` Srikar Dronamraju
2020-07-31 7:36 ` Gautham R Shenoy
2020-07-27 5:32 ` [PATCH v4 10/10] powerpc/smp: Implement cpu_to_coregroup_id Srikar Dronamraju
2020-07-31 8:02 ` Michael Ellerman
2020-07-31 9:58 ` Srikar Dronamraju
2020-07-31 11:29 ` Michael Ellerman
2020-07-30 17:22 ` [PATCH v4 00/10] Coregroup support on Powerpc Srikar Dronamraju
-- strict thread matches above, loose matches on Subject: below --
2020-07-27 5:17 Srikar Dronamraju
2020-07-27 5:18 ` [PATCH v4 06/10] powerpc/smp: Generalize 2nd sched domain Srikar Dronamraju
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