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Subject[PATCH 7/7] powerpc/smp: Depend on cpu_l1_cache_map when adding cpus
Date
Currently on hotplug/hotunplug, the cpu iterates through all the cpus in
its core to find threads in its thread group. However this info is
already captured in cpu_l1_cache_map. Hence we could reduce the
iteration and cleanup add_cpu_to_smallcore_masks function.

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: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
arch/powerpc/kernel/smp.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index eceb7aa0f4b8..22f4b3856470 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1276,16 +1276,15 @@ static void remove_cpu_from_masks(int cpu)

static inline void add_cpu_to_smallcore_masks(int cpu)
{
- struct cpumask *this_l1_cache_map = per_cpu(cpu_l1_cache_map, cpu);
- int i, first_thread = cpu_first_thread_sibling(cpu);
+ int i;

if (!has_big_cores)
return;

cpumask_set_cpu(cpu, cpu_smallcore_mask(cpu));

- for (i = first_thread; i < first_thread + threads_per_core; i++) {
- if (cpu_online(i) && cpumask_test_cpu(i, this_l1_cache_map))
+ for_each_cpu(i, per_cpu(cpu_l1_cache_map, cpu)) {
+ if (cpu_online(i))
set_cpus_related(i, cpu, cpu_smallcore_mask);
}
}
--
2.17.1
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