kern/74986: sysctlize a parameter of if_em's interrupt moderation

[Shunsuke SHINOMIYA]

>Number:         74986
>Category:       kern
>Synopsis:       sysctlize a parameter of if_em's interrupt moderation
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Dec 12 14:30:26 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Shunsuke SHINOMIYA
>Release:        FreeBSD 5.3-RELEASE i386
>Organization:
>Environment:
System: FreeBSD zipper.net.ss.titech.ac.jp 5.3-RELEASE FreeBSD 5.3-RELEASE #28: Mon Nov 15 15:50:34 JST 2004 shino at zipper.net.ss.titech.ac.jp:/usr/obj/usr/src/sys/PM i386


	
>Description:
This change sysctlize last one of the parameter of if_em's interrupt moderation .

sysctl hw.em?.int_throttle_ceil corresponds to the `absolute timer' at AP450(*1), application note by intel.
*1 ftp://download.intel.com/design/network/applnots/ap450.pdf

`absolute timer' is for suppressing rate of interrupt per unit of time.
The value of int_throttle_ceil means a ceiling of the number of interrupt fireing per unit of time.

Default value of int_throttle_ceil is 8000. Setting int_throttle_ceil 0 means disabling throttle moderation concerning the absolute timer.

>How-To-Repeat:
	
>Fix:
The diff of URL shown below adds sysctl int_throttle_ceil to hw.em?.

http://www.fornext.org/patch/if_em.diff

>Release-Note:
>Audit-Trail:
>Unformatted: