Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning
Constants used for tuning are generally a bad idea, especially as hardware
changes over time. Replace the constant 2 jiffies with sysctl variable
netdev_budget_usecs to enable sysadmins to tune the softirq processing.
Also document the variable.
For example, a very fast machine might tune this to 1000 microseconds,
while my regression testing 486DX-25 needs it to be 4000 microseconds on
a nearly idle network to prevent time_squeeze from being incremented.
Version 2: changed jiffies to microseconds for predictable units.
Signed-off-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 5d33e2b..1c53c05 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3441,6 +3441,7 @@ EXPORT_SYMBOL(netdev_max_backlog);
int netdev_tstamp_prequeue __read_mostly = 1;
int netdev_budget __read_mostly = 300;
+unsigned int __read_mostly netdev_budget_usecs = 2000;
int weight_p __read_mostly = 64; /* old backlog weight */
int dev_weight_rx_bias __read_mostly = 1; /* bias for backlog weight */
int dev_weight_tx_bias __read_mostly = 1; /* bias for output_queue quota */
@@ -5307,7 +5308,8 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll)
static __latent_entropy void net_rx_action(struct softirq_action *h)
{
struct softnet_data *sd = this_cpu_ptr(&softnet_data);
- unsigned long time_limit = jiffies + 2;
+ unsigned long time_limit = jiffies +
+ usecs_to_jiffies(netdev_budget_usecs);
int budget = netdev_budget;
LIST_HEAD(list);
LIST_HEAD(repoll);