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authorMatthew Whitehead <tedheadster@gmail.com>2017-04-19 12:37:10 -0400
committerDavid S. Miller <davem@davemloft.net>2017-04-21 13:22:34 -0400
commit7acf8a1e8a28b3d7407a8d8061a7d0766cfac2f4 (patch)
tree34fb2d27d86e816f25b4a41f0d5d6b8d837f5bd9 /net
parent20da848f8e5c2d911ee65dda1776d0f2a2408e01 (diff)
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>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c4
-rw-r--r--net/core/sysctl_net_core.c8
2 files changed, 11 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 5d33e2baab2b..1c53c055b197 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 @@ out_unlock:
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);
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 7f9cc400eca0..ea23254b2457 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -452,6 +452,14 @@ static struct ctl_table net_core_table[] = {
.extra1 = &one,
.extra2 = &max_skb_frags,
},
+ {
+ .procname = "netdev_budget_usecs",
+ .data = &netdev_budget_usecs,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ },
{ }
};