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authorMatthew Whitehead <tedheadster@gmail.com>2017-04-19 19:37:10 +0300
committerDavid S. Miller <davem@davemloft.net>2017-04-21 20:22:34 +0300
commit7acf8a1e8a28b3d7407a8d8061a7d0766cfac2f4 (patch)
tree34fb2d27d86e816f25b4a41f0d5d6b8d837f5bd9 /Documentation/sysctl
parent20da848f8e5c2d911ee65dda1776d0f2a2408e01 (diff)
downloadlinux-7acf8a1e8a28b3d7407a8d8061a7d0766cfac2f4.tar.xz
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 'Documentation/sysctl')
-rw-r--r--Documentation/sysctl/net.txt11
1 files changed, 10 insertions, 1 deletions
diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index 2ebabc93014a..14db18c970b1 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -188,7 +188,16 @@ netdev_budget
Maximum number of packets taken from all interfaces in one polling cycle (NAPI
poll). In one polling cycle interfaces which are registered to polling are
-probed in a round-robin manner.
+probed in a round-robin manner. Also, a polling cycle may not exceed
+netdev_budget_usecs microseconds, even if netdev_budget has not been
+exhausted.
+
+netdev_budget_usecs
+---------------------
+
+Maximum number of microseconds in one NAPI polling cycle. Polling
+will exit when either netdev_budget_usecs have elapsed during the
+poll cycle or the number of packets processed reaches netdev_budget.
netdev_max_backlog
------------------