Sponsored Content
Operating Systems Linux kernel:how to modify and read the tick rate:HZ Post 302156391 by amit4g on Tuesday 8th of January 2008 04:20:17 AM
Old 01-08-2008
kernel:how to modify and read the tick rate:HZ

hi,

one of our customer is facing an issue with jiffies wrap up.
on a 32 bit machine, the variable jiffies count upto 472 days.
the customer's server was up for 472 days ('uptime') and to reproduce
the same, i tried to change the variable HZ in linux-2.6..23.9/include/asm-i386/param.h
from 100 to 10000.
after which i rebuilt the kernel with following steps:
# make oldconfig
# make modules_install
# make install

Now when i boot from this newly built kernel, i wrote a small kernel module
to read the jiffies and HZ global variable,which is as follows:

[root@localhost drivers]# cat get_jiffies.c
#include <linux/init.h>
#include <linux/module.h>
#include <asm/current.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/jiffies.h>
static int __init jiffies_init(void)
{
unsigned long j,z;
j = z = 0;
j = jiffies;
z = HZ;
printk(KERN_ALERT "jiffies value is %lu\n",j);
printk(KERN_ALERT "jiffies value in seconds %lu\n",(jiffies/HZ));
printk(KERN_ALERT "HZ value is %lu\n",z);
return 0;
}

static void __exit jiffies_exit(void)
{
printk(KERN_ALERT "Goodbye, world!\n");
}

module_init(jiffies_init);
module_exit(jiffies_exit);

MODULE_LICENSE("GPL");

[root@localhost drivers]# insmod get_jiffies.ko
[root@localhost drivers]# dmesg
jiffies value is 372939
jiffies value in seconds 1491
HZ value is 250 <====

why this HZ variable is shown as 250 ?
i am a newbie in kernel programming and i might be doing something really stupid as well.


~amit
 

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

HELP! Need 2 Write a program which will read in a tax rate (as a percentage) and the

I need this ASAP...don't know where else to turn... Thanx in advance :) (2 Replies)
Discussion started by: 1TruLuv
2 Replies

2. Shell Programming and Scripting

How to read a specific section and modify within

Hi, I am n00b to shell scripting and I am learning Ksh, sed and awk. I have a requirement and need your help. 1) How to read a specific section of a file. I have a file and I want to read the contents between say "Page Number:1" to "End of Page 1" 2) Within the section of the file that was... (2 Replies)
Discussion started by: kn.naresh
2 Replies

3. UNIX for Advanced & Expert Users

How to read freebsd kernel source?

I got the freebsd kernel source from the first install CD(in directory:\7.0-RELEASE\src\),isn't right? if so,how can i read it? Is there any tools? (1 Reply)
Discussion started by: zhouq3132
1 Replies

4. UNIX for Dummies Questions & Answers

How to read freebsd kernel source?

I got the freebsd kernel source from the first install CD(in directory:\7.0-RELEASE\src\),isn't right? if so,how can i read it? Is there any tools? (4 Replies)
Discussion started by: zhouq3132
4 Replies

5. UNIX for Dummies Questions & Answers

Understanding read/write and kernel interaction

Ok, so I'm trying to finalize my understanding of read/write and kernel interaction. read(): You have a library function that has as it's first parameter (what the open file to read from is), second parameter( a pointer to a buffer (is this the location of a buffer in the user area or the... (1 Reply)
Discussion started by: Krothos
1 Replies

6. Programming

Understanding read/write and kernel interaction

Ok, so I'm trying to finalize my understanding of read/write and kernel interaction. read(): You have a library function that has as it's first parameter (what the open file to read from is), second parameter( a pointer to a buffer (is this the location of a buffer in the user area or the... (7 Replies)
Discussion started by: Krothos
7 Replies

7. Solaris

Which file is read by kernel to set its default system kernel parameters values?

Hi gurus Could anybody tell me which file is read by kernel to set its default system kernal parameters values in solaris. Here I am not taking about /etc/system file which is used to load kernal modules or to change any default system kernal parameter value Is it /dev/kmem file or something... (1 Reply)
Discussion started by: girish.batra
1 Replies

8. Shell Programming and Scripting

Read data from .csv file through shell script & modify

I need to read data from a file called "test.csv" through shell script where the file contains values like name,price,descriptor etc. There are rows where descriptor (& in some rows name) are written as string & other characters like "car_+" OR "bike*" etc where it should contains strings like... (3 Replies)
Discussion started by: raj100
3 Replies

9. Windows & DOS: Issues & Discussions

Clock doesn't tick

This is a strange one, I've never seen anything like it; the realtime clock doesn't tick while the computer's idle, only when you're watching it. Leave for 3 hours and it'll be 3 hours off. It still advances when it's off however, or the time would be far more incorrect than it is. About all... (10 Replies)
Discussion started by: Corona688
10 Replies

10. Homework & Coursework Questions

C++ Attempting to modify this function to read from a (;) semi-colon-separated file

After some thought. I am uncomfortable issuing my professors name where, there may be unintended side effects from any negative responses/feedback. Willing to re post if I can omit school / professor publicly, but can message moderator for validation? I am here for knowledge and understanding,... (1 Reply)
Discussion started by: briandanielz
1 Replies
fruadm(1M)						  System Administration Commands						fruadm(1M)

NAME
fruadm - prints and updates customer data associated with FRUs SYNOPSIS
/usr/platform/sun4u/sbin/fruadm /usr/platform/sun4u/sbin/fruadm -l /usr/platform/sun4u/sbin/fruadm [-r] path [text] DESCRIPTION
fruadm prints or sets the customer data for Field-Replaceable Units (FRUs). Without arguments, fruadm prints the paths of all FRU ID-capable FRUs (containers) in the system, along with the contents of the customer data record, if present, for each such FRU; for FRUs without customer data, fruadm prints only the container's path. Only a privileged user can create or update data in containers. The privileges required to perform these write operations are hardware dependent. Typically, a default system configuration restricts write operations to the superuser or to the platform-administrator user. OPTIONS
The following options are supported: -l List the system's frutree paths. -r Recursively display or update the data for all containers rooted at the argument path. OPERANDS
The following operands are supported: path A full or partial system frutree path for or under which to print or set the customer data. The first field of each line of output of fruadm -l gives the valid full frutree paths for the system. Paths can include shell meta-characters; such paths should be quoted appropriately for the user's shell. For par- tial paths, the first matching full path is selected for display or update. Without the -r option, the path must be that of a container; with the -r option, all containers (if any) under path will be selected. text Up to 80 characters of text set as the customer data. If the text contains white space or shell metacharacters, it should be quoted appropriately for the user's shell. EXAMPLES
Example 1: Displaying All Customer Data The following example prints all customer data available from FRUs on the system. For containers with no customer data, only the contain- ers' paths will be listed. example% fruadm Example 2: Displaying Customer Data For a Single FRU The following command prints the customer data, if present, for the specified FRU: example% fruadm /frutree/chassis/system-board Example 3: Displaying Customer Data For a Single FRU The following command prints the customer data, if present, for the first mem-module found: example% fruadm mem-module Example 4: Setting Customer Data The following example sets the customer data for a FRU: example# fruadm system-board 'Asset Tag 123456' Example 5: Setting Customer Data The following command sets the customer data for all FRUs under chassis: example# fruadm -r /frutree/chassis "Property of XYZ, Inc." EXIT STATUS
The following exit values are returned: 0 Successful completion. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWfruip.u | +-----------------------------+-----------------------------+ |Interface Stability |Unstable | +-----------------------------+-----------------------------+ SEE ALSO
prtfru(1M), attributes(5) SunOS 5.10 22 Feb 2002 fruadm(1M)
All times are GMT -4. The time now is 08:04 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy