netdev - [PATCH net-next] net: don't set sw irq coalescing defaults in case of PREEMPT

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Message-ID: <f9439c7f-c92c-4c2c-703e-110f96d841b7@gmail.com>
Date: Sun, 28 May 2023 19:39:59 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, David Miller <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next] net: don't set sw irq coalescing defaults in case of
 PREEMPT_RT

If PREEMPT_RT is set, then assume that the user focuses on minimum
latency. Therefore don't set sw irq coalescing defaults.
This affects the defaults only, users can override these settings
via sysfs.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 net/core/dev.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index b3c13e041..58f71d619 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10568,8 +10568,10 @@ void netdev_sw_irq_coalesce_default_on(struct net_device *dev)
 {
 	WARN_ON(dev->reg_state == NETREG_REGISTERED);
 
-	dev->gro_flush_timeout = 20000;
-	dev->napi_defer_hard_irqs = 1;
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		dev->gro_flush_timeout = 20000;
+		dev->napi_defer_hard_irqs = 1;
+	}
 }
 EXPORT_SYMBOL_GPL(netdev_sw_irq_coalesce_default_on);
 
-- 
2.40.1