netdev - Re: [PATCH net-next] Replace 2 jiffies with sysctl netdev_budget

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Message-ID: <1492804622.6453.32.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 21 Apr 2017 12:57:02 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     tedheadster@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] Replace 2 jiffies with sysctl
 netdev_budget_usecs to enable softirq tuning

On Fri, 2017-04-21 at 13:22 -0400, David Miller wrote:
> From: Matthew Whitehead <tedheadster@...il.com>
> Date: Wed, 19 Apr 2017 12:37:10 -0400
> 
> > 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@...il.com>
> 
> Applied, thanks.

Can we revert the changes in kernel/sysctl_binary.c &
include/uapi/linux/sysctl.h ?

{ CTL_INT,      NET_CORE_BUDGET_USECS,  "netdev_budget_usecs" },

NET_CORE_BUDGET_USECS=23,

Unless I am missing something, we should not add new binary sysctls.


Thanks.