From 7acf8a1e8a28b3d7407a8d8061a7d0766cfac2f4 Mon Sep 17 00:00:00 2001 From: Matthew Whitehead Date: Wed, 19 Apr 2017 12:37:10 -0400 Subject: 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 Signed-off-by: David S. Miller --- Documentation/sysctl/net.txt | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'Documentation/sysctl') diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt index 2ebabc9..14db18c 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 ------------------ -- cgit v1.1