linux-kernel - [PATCH v3 05/11] powerpc/smp: Limit CPUs traversed to within a node.

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Message-Id: <20201007183800.27415-6-srikar@linux.vnet.ibm.com>
Date:   Thu,  8 Oct 2020 00:07:54 +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>,
        Satheesh Rajendran <sathnaga@...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>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Qian Cai <cai@...hat.com>
Subject: [PATCH v3 05/11] 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.

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Tested-by: Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
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>
Cc: Qian Cai <cai@...hat.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 2e61a81aad88..c860c4950c9f 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1241,7 +1241,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
 	}
 
 	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