netdev - [PATCH] ixgbe: take online CPU number as MQ max limit when alloc_etherdev

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Date:	Fri, 13 May 2016 14:56:35 +0900
From:	Ethan Zhao <ethan.zhao@...cle.com>
To:	jeffrey.t.kirsher@...el.com, jesse.brandeburg@...el.com,
	shannon.nelson@...el.com, carolyn.wyborny@...el.com,
	donald.c.skidmore@...el.com, bruce.w.allan@...el.com,
	john.ronciak@...el.com, mitch.a.williams@...el.com,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, ethan.kernel@...il.com,
	ethan.zhao@...cle.com
Subject: [PATCH] ixgbe: take online CPU number as MQ max limit when  alloc_etherdev_mq()

Allocating 64 Tx/Rx as default doesn't benefit perfomrnace when less
CPUs were assigned. especially when DCB is enabled, so we should take
num_online_cpus() as top limit, and aslo to make sure every TC has
at least one queue, take the MAX_TRAFFIC_CLASS as bottom limit of queues
number.

Signed-off-by: Ethan Zhao <ethan.zhao@...cle.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 7df3fe2..1f9769c 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -9105,6 +9105,10 @@ static int ixgbe_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		indices = IXGBE_MAX_RSS_INDICES;
 #endif
 	}
+	/* Don't allocate too more queues than online cpus number */
+	indices = min_t(int, indices, num_online_cpus());
+	/* To make sure TC works, allocate at least 1 queue per TC */
+	indices = max_t(int, indices, MAX_TRAFFIC_CLASS);
 
 	netdev = alloc_etherdev_mq(sizeof(struct ixgbe_adapter), indices);
 	if (!netdev) {
-- 
1.8.3.1