linux tasklet 4
引用 2 楼 cokeliu 的回复:
谢谢! 请问是否每调用一次tasklet_schedule(B task); B task任务被加到链表上只会被执行一次?
是的，只被加一次
第一次tasklet_schedule(B task)给他一个状态TASK_STATE_SCHED
作标记，以后的tasklet_schedule(B task)会检查这个标记
http://os.inf.tu-dresden.de/l4env/doc/html/dde_linux/group__mod__softirq.html
Deferred Activities
[Linux DDE Common
]
This module emulates deferred activities
at interrupt level inside the Linux kernel.
More...
Softirqs
This is from include/linux/interrupt.h
Softirqs are multithreaded, not serialized BH-like activities. Several
softirqs may run on several CPUs simultaneously - no matter if they are
of the same type.
Properties:
If raise_softirq()
is called, then softirq is guarenteed to be executed on this CPU.
On schedule()
do_softirq() is called if any softirq is active on this CPU.
Softirqs are not serialized in any way.
Linux (2.4.20) has only 4 softirqs:
HI_SOFTIRQ
NET_TX_SOFTIRQ
and NET_RX_SOFTIRQ
TASKLET_SOFTIRQ
Relevant for Linux DDE are for now only the first and the latter - NET_*
softirqs allow transparent mutli-threading in Linux' network code. HI_SOFTIRQ
is for high priority bottom halves as old-style
BHs and sound related drivers. It triggers execution of tasklet_hi_action()
. TASKLET_SOFTIRQ
runs lower priority bottom halves (e.g. in the console subsystem). It triggers execution of tasklet_action()
.
Todo:
only the implementation of tasklets is done in Linux DDE
void
raise_softirq
(int nr)
Raise Softirq.
Tasklets
This is from kernel/softirq.c and include/linux/interrupt.h)
Tasklets are the multithreaded analogue of BHs.
Main feature differing them of generic softirqs: one tasklet is running only on one CPU simultaneously.
Main feature differing them of BHs: different tasklets may be run simultaneously on different CPUs.
Properties:
If tasklet_schedule()
is called, then tasklet is guaranteed to be executed on some cpu at least on
相关文档：
在某些特殊的情况下，如因为网络或者X配置的关系无法连接到X server或者主机上没有X，就可以使用静默安装的方式安装数据库，同样如果需要大规模部署，则静默安装将会大大减轻DBA的重复劳动力，而且静默安装不需要X，从安装效率
在某些特殊的情况下，如因为网络或者X配置的关系无法连接到X server或者主机上没有X� ......
errno变量(需include errno.h)会被赋一个整数值,不同的值表示不同的含义,
可以通过查看该值推测出错的原因。但是errno是一个数字，代表的具体含义
还要到errno.h中去阅读宏定义。有下面几种方法可以方便的得到错误信息
(一)
#include <stdio.h>
void perror(const char *s)
perror()用来将上一个函数发生错误的 ......
递归查找文件内容：
grep -n -ri "slewing" ./
在当前目下递归查找所有的文件
-i, --ignore-case
Ignore case distinctions ......
http://blog.chinaunix.net/u/24474/showart_227121.html
驱动程序使用tasklet机制
转自：http://blog.chinaunix.net/u/15169/showart.php?id=82989
驱
动程序在初始化时，通过函数task_init建立一个tasklet，然后调用函数tasklet_schedule将这个tasklet放在
tasklet_vec链表的头部，并唤醒后台线程ksoftirqd。当后台� ......
原帖：http://www.cnscn.org/read.php?tid-44684.html
iptables有三种链
1：INPUT (进来的链)
2：OUTPUT(出去的链)
3：FORWARD(转发的链)
iptables -A INPUT -p icmp -j DROP
-A(添加一个链) -p 协议 -j(添加动作) 说明添加一个进来的链。协议是icmp动作拒绝。
iptables -L -n (用树形结构来看一下iptables的设置)
......
