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gve: Cache link_speed value from device 

[ Upstream commit 68c3e4fc86 ]

The link speed is never changed for the uptime of a VM, and the current
implementation sends an admin queue command for each call. Admin queue
command invocations have nontrivial overhead (e.g., VM exits), which can
be disruptive to users if triggered frequently. Our telemetry data shows
that there are VMs that make frequent calls to this admin queue command.
Caching the result of the original admin queue command would eliminate
the need to send multiple admin queue commands on subsequent calls to
retrieve link speed.

Fixes: 7e074d5a76 ("gve: Enable Link Speed Reporting in the driver.")
Signed-off-by: Joshua Washington <joshwash@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230321172332.91678-1-joshwash@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
pull/1175/head
Joshua Washington 2023-03-21 10:23:32 -07:00 committed by Greg Kroah-Hartman
parent 554828c833
commit 1b9613402c
1 changed files with 4 additions and 1 deletions
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5
drivers/net/ethernet/google/gve/gve_ethtool.c
View File

@ -535,7 +535,10 @@ static int gve_get_link_ksettings(struct net_device *netdev,
struct ethtool_link_ksettings *cmd)
{
struct gve_priv *priv = netdev_priv(netdev);
int err = gve_adminq_report_link_speed(priv);
int err = 0;
if (priv->link_speed == 0)
err = gve_adminq_report_link_speed(priv);
cmd->base.speed = priv->link_speed;
return err;