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From: Yury Norov <yury.norov@gmail.com>
To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Naveen N Rao <naveen@kernel.org>,
	Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Yury Norov <yury.norov@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: [PATCH 04/14] powerpc/xmon: simplify xmon_batch_next_cpu()
Date: Sat, 28 Dec 2024 10:49:36 -0800	[thread overview]
Message-ID: <20241228184949.31582-5-yury.norov@gmail.com> (raw)
In-Reply-To: <20241228184949.31582-1-yury.norov@gmail.com>

The function opencodes for_each_cpu_wrap() macro. As a loop termination
condition it uses cpumask_empty(), which is O(N), and it makes the whole
algorithm O(N^2). Switching to for_each_cpu_wrap() simplifies the logic,
and makes the algorithm linear.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 arch/powerpc/xmon/xmon.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index f4e841a36458..d7809f15dc68 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1271,11 +1271,7 @@ static int xmon_batch_next_cpu(void)
 {
 	unsigned long cpu;
 
-	while (!cpumask_empty(&xmon_batch_cpus)) {
-		cpu = cpumask_next_wrap(smp_processor_id(), &xmon_batch_cpus,
-					xmon_batch_start_cpu, true);
-		if (cpu >= nr_cpu_ids)
-			break;
+	for_each_cpu_wrap(cpu, &xmon_batch_cpus, xmon_batch_start_cpu) {
 		if (xmon_batch_start_cpu == -1)
 			xmon_batch_start_cpu = cpu;
 		if (xmon_switch_cpu(cpu))
-- 
2.43.0


  parent reply	other threads:[~2024-12-28 18:50 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-28 18:49 [PATCH 00/14] cpumask: cleanup cpumask_next_wrap() implementation and usage Yury Norov
2024-12-28 18:49 ` [PATCH 01/14] objpool: rework objpool_pop() Yury Norov
2024-12-28 18:49 ` [PATCH 02/14] virtio_net: simplify virtnet_set_affinity() Yury Norov
2024-12-28 18:49 ` [PATCH 03/14] ibmvnic: simplify ibmvnic_set_queue_affinity() Yury Norov
2025-01-07 22:37   ` Nick Child
2025-01-07 22:42     ` Yury Norov
2025-01-07 23:04       ` Yury Norov
2025-01-08 14:08         ` [PATCH 03/14] ibmvnic: simplify ibmvnic_set_queue_affinity()y Nick Child
2024-12-28 18:49 ` Yury Norov [this message]
2024-12-28 18:49 ` [PATCH 05/14] cpumask: deprecate cpumask_next_wrap() Yury Norov
2025-01-03 17:39   ` Bjorn Helgaas
2024-12-28 18:49 ` [PATCH 06/14] cpumask: re-introduce cpumask_next{,_and}_wrap() Yury Norov
2025-01-03 17:44   ` Bjorn Helgaas
2025-01-15  3:41     ` Yury Norov
2025-01-07 13:28   ` Alexander Gordeev
2025-01-15  3:38     ` Yury Norov
2024-12-28 18:49 ` [PATCH 07/14] cpumask: use cpumask_next_wrap() where appropriate Yury Norov
2024-12-28 18:49 ` [PATCH 08/14] padata: switch padata_find_next() to using cpumask_next_wrap() Yury Norov
2025-01-04  0:33   ` Herbert Xu
2025-01-07 19:02   ` Daniel Jordan
2024-12-28 18:49 ` [PATCH 09/14] s390: switch stop_machine_yield() " Yury Norov
2024-12-28 18:49 ` [PATCH 10/14] nvme-tcp: switch nvme_tcp_set_queue_io_cpu() " Yury Norov
2024-12-30  8:31   ` Sagi Grimberg
2024-12-28 18:49 ` [PATCH 11/14] scsi: lpfc: switch lpfc_irq_rebalance() " Yury Norov
2024-12-31  1:05   ` Justin Tee
2024-12-28 18:49 ` [PATCH 12/14] scsi: lpfc: rework lpfc_next_{online,present}_cpu() Yury Norov
2024-12-31  1:06   ` Justin Tee
2024-12-28 18:49 ` [PATCH 13/14] PCI: hv: switch hv_compose_multi_msi_req_get_cpu() to using cpumask_next_wrap() Yury Norov
2024-12-29 17:34   ` Michael Kelley
2025-01-03 17:45   ` Bjorn Helgaas
2025-01-03 18:56     ` Yury Norov
2024-12-28 18:49 ` [PATCH 14/14] cpumask: drop cpumask_next_wrap_old() Yury Norov
2025-01-03  7:02 ` [PATCH 00/14] cpumask: cleanup cpumask_next_wrap() implementation and usage Christoph Hellwig
2025-01-03 15:21   ` Yury Norov

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