linux-kernel - [PATCH net-next 2/2] net: core: increase the default size of GRO

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Date:   Thu, 10 Oct 2019 17:42:26 +0300
From:   Alexander Lobakin <alobakin@...nk.ru>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Edward Cree <ecree@...arflare.com>, Jiri Pirko <jiri@...lanox.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Ido Schimmel <idosch@...lanox.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Petr Machata <petrm@...lanox.com>,
        Sabrina Dubroca <sd@...asysnail.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Lobakin <alobakin@...nk.ru>
Subject: [PATCH net-next 2/2] net: core: increase the default size of GRO_NORMAL skb lists to flush

Commit 323ebb61e32b ("net: use listified RX for handling GRO_NORMAL
skbs") have introduced a sysctl variable gro_normal_batch for defining
a limit for listified Rx of GRO_NORMAL skbs. The initial value of 8 is
purely arbitrary and has been chosen, I believe, as a minimal safe
default.
However, several tests show that it's rather suboptimal and doesn't
allow to take a full advantage of listified processing. The best and
the most balanced results have been achieved with a batches of 16 skbs
per flush.
So double the default value to give a yet another boost for Rx path.
It remains configurable via sysctl anyway, so may be fine-tuned for
each hardware.

Signed-off-by: Alexander Lobakin <alobakin@...nk.ru>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index a33f56b439ce..4f60444bb766 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4189,7 +4189,7 @@ int dev_weight_tx_bias __read_mostly = 1;  /* bias for output_queue quota */
 int dev_rx_weight __read_mostly = 64;
 int dev_tx_weight __read_mostly = 64;
 /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
-int gro_normal_batch __read_mostly = 8;
+int gro_normal_batch __read_mostly = 16;

 /* Called with irq disabled */
 static inline void ____napi_schedule(struct softnet_data *sd,
-- 
2.23.0