linux-kernel - [PATCH 5/7] powerpc/smp: Limit cpus traversed to within a node.

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Date:   Mon, 27 Jul 2020 13:25:30 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Anton Blanchard <anton@...abs.org>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Nathan Lynch <nathanl@...ux.ibm.com>,
        Michael Neuling <mikey@...ling.org>,
        Gautham R Shenoy <ego@...ux.vnet.ibm.com>,
        Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>
Subject: [PATCH 5/7] powerpc/smp: Limit cpus traversed to within a node.

All the arch specific topology cpumasks are within a node/die.
However when setting these per cpu cpumasks, system traverses through
all the online cpus. This is redundant.

Reduce the traversal to only cpus that are online in the node to which
the cpu belongs to.

Cc: linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Anton Blanchard <anton@...abs.org>
Cc: Oliver O'Halloran <oohall@...il.com>
Cc: Nathan Lynch <nathanl@...ux.ibm.com>
Cc: Michael Neuling <mikey@...ling.org>
Cc: Gautham R Shenoy <ego@...ux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Valentin Schneider <valentin.schneider@....com>
Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
 arch/powerpc/kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index cde157483abf..9b03aad0beac 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1232,7 +1232,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
 		return false;
 
 	cpumask_set_cpu(cpu, mask_fn(cpu));
-	for_each_cpu(i, cpu_online_mask) {
+	for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
 		/*
 		 * when updating the marks the current CPU has not been marked
 		 * online, but we need to update the cache masks
-- 
2.17.1