Jan
24
Posted on 24-01-2011
Filed Under (Redhat & Fedora, RPM & Deb Packages, UNIX/Linux) by Ravi Bhure

Introduction –
Fedora’s package management tools — including yum, pup, and pirut  — are all based on the RPM package format and management system. One little-known secret about RPM is that it can be configured to repackage  files from an RPM package during package uninstallation, saving the (possibly modified) files into a new RPM package. The repackaged RPM incorporates any changes that you have made to the configuration files, scripts, and data files that were originally included with the software. This means that it’s possible to rollback the uninstallation of software, which will restore the package to the state it was in before it was removed.

The rollback mechanism can also undo package installations by uninstalling the newly-installed packages, and since a software update is a performed by installing a new package version and then removing the old one, the rollback mechanism can also undo package updates.

Open /etc/yum.conf file and put below two line

#yum rollback select enable
tsflags=repackage

or append it a simple way 🙂

[root@testbed ~]# echo “tsflags=repackage” >> /etc/yum.conf

Now create or edit /etc/rpm/macros and put “%_repackage_all_erasures 1” entry in it.

[root@testbed ~]# echo “%_repackage_all_erasures 1” >> /etc/rpm/macros

[root@testbed ~]# cat /etc/rpm/macros
%_repackage_all_erasures 1

Repackaged files are stored in /var/spool/repackage

[root@testbed ~]# ll -ld /var/spool/repackage
drwxr-xr-x 2 root root 4096 Sep  4  2009 /var/spool/repackage

Now we are test it with python packages, (I have used centos 5.5 for it)

[root@testbed ~]# yum -y install python*

Installed:
python-dmidecode.i386 0:3.10.13-1.el5_5.1           python-docs.noarch 0:2.4.3-1.1                    python-exo.i386 0:0.3.4-1.el5.centos
python-imaging.i386 0:1.1.5-5.el5                   python-imaging-devel.i386 0:1.1.5-5.el5           python-lcms.i386 0:1.18-0.1.beta1.el5_3.2
python-pyblock.i386 0:0.26-4.el5                    python-setuptools.noarch 0:0.6c5-2.el5            python-tools.i386 0:2.4.3-27.el5_5.3

Dependency Installed:
exo.i386 0:0.3.4-1.el5.centos                     libbdevid-python.i386 0:5.1.19.6-61.el5_5.2            libxfce4mcs.i386 0:4.4.2-1.el5.centos
libxfce4util.i386 0:4.4.2-1.el5.centos            libxfcegui4.i386 0:4.4.2-1.el5.centos                  tix.i386 1:8.4.0-11.fc6
tkinter.i386 0:2.4.3-27.el5_5.3

Updated:
python.i386 0:2.4.3-27.el5_5.3                python-devel.i386 0:2.4.3-27.el5_5.3                python-virtinst.noarch 0:0.400.3-9.el5_5.1

Dependency Updated:
mkinitrd.i386 0:5.1.19.6-61.el5_5.2                                             nash.i386 0:5.1.19.6-61.el5_5.2

Complete!
[root@testbed ~]# ls /var/spool/repackage/
mkinitrd-5.1.19.6-61.i386.rpm  python-2.4.3-27.el5.i386.rpm        python-virtinst-0.400.3-9.el5.noarch.rpm
nash-5.1.19.6-61.i386.rpm      python-devel-2.4.3-27.el5.i386.rpm

Yum Roll Back options available:

* rpm -Uhv –rollback ‘9:00 am’
* rpm -Uhv –rollback ‘4 hours ago’
* rpm -Uhv –rollback ‘december 25’

[root@testbed ~]# date
Mon Jan 24 12:10:19 IST 2011

Now we reverting package rollback to a previous state.

[root@testbed ~]# rpm -Uhv –rollback ‘9:00 am’
Rollback packages (+5/-21) to Mon Jan 24 11:58:17 2011 (0x4d3d1c01):
Preparing…                ########################################### [100%]
1:nash                   ########################################### [ 10%]
2:python                 ########################################### [ 20%]
3:mkinitrd               ########################################### [ 30%]
4:python-devel           ########################################### [ 40%]
5:python-virtinst        ########################################### [ 50%]
Cleaning up repackaged packages:
Removing /var/spool/repackage/mkinitrd-5.1.19.6-61.i386.rpm:
Removing /var/spool/repackage/nash-5.1.19.6-61.i386.rpm:
Removing /var/spool/repackage/python-2.4.3-27.el5.i386.rpm:
Removing /var/spool/repackage/python-devel-2.4.3-27.el5.i386.rpm:
Removing /var/spool/repackage/python-virtinst-0.400.3-9.el5.noarch.rpm:

Now you can check your previous versions of python & mkinitrd, nash packages.

[root@testbed ~]# rpm -qa|grep -E ‘python|mkinitrd|nash’

The repackage/rollback approach is far from perfect — for example, data files created and used with a package (but not in files provided as part of the package) are not saved during repackaging, and some RPM scripts assume that packages are only upgraded and never downgraded. Nonetheless, package rollback can be a very useful feature, especially when an update breaks something that used to work.
Repackaging can take a lot of space, so it’s disabled by default, and there is no way to enable it or to perform a rollback from the command line. Here, in a nutshell, are instructions for using this feature:

Ref: http://dailypackage.fedorabook.com/index.php?/archives/17-Wednesday-Why-Repackaging-and-Rollbacks.html

-Ravi

(1) Comment    Read More   
Jan
08
Posted on 08-01-2011

** What is oprofile

In short “oprofile is a system-wide profiler”
need to profile an application and its shared libraries, examine hardware effects such as cache misses and capture the performance behaviour of entire system, then surely you need go with oprofile.

There is to many options and conditions spcefied, where we use only simple and easy one for further details, Please Read Man Pages 😉

Many CPUs provide “performance counters”, hardware registers that can count “events”; for example, cache misses, or CPU cycles. OProfile provides profiles of code based on the number of these occurring events: repeatedly, every time a certain (configurable) number of events has occurred, the PC value is recorded. This information is aggregated into profiles for each binary image.

Some hardware setups do not allow OProfile to use performance counters: in these cases, no events are available, and OProfile operates in timer/RTC mode

** All Docs, Examples and Bugs you will find @ http://oprofile.sourceforge.net

# download tar from http://oprofile.sourceforge.net/download/ or you can install it using yum also

[root@ravi.com ~]# yum install oprofile

Before you can use OProfile, you must set it up. The minimum setup required for this is to tell OProfile where the vmlinux file corresponding to the running kernel is, for example :

[root@ravi.com ~]#  opcontrol –vmlinux=/boot/vmlinux-`uname -r`

If you don’t want to profile the kernel itself, you can tell OProfile you don’t have a vmlinux file :

[root@ravi.com ~]# opcontrol –no-vmlinux

Here we used –no-vmlinux and specified other session directory than default location (/var/lib/oprofile)

[root@ravi.com ~]# opcontrol –no-vmlinux –session-dir=/home/prod/tmpsession

Now we are ready to start the daemon (oprofiled) which collects the profile data :

[root@ravi.com ~]# opcontrol –start –session-dir=/home/prod/tmpsession
Using default event: GLOBAL_POWER_EVENTS:100000:1:1:1
Using 2.6+ OProfile kernel interface.
Using log file /home/prod/tmpsession/samples/oprofiled.log
Daemon started.
Profiler running.

When I want to stop profiling, I can do so with :
(Here I have ran opcontrol only 1 min)
[root@ravi.com ~]# opcontrol –shutdown
Stopping profiling.
Killing daemon.

Lets see what your system & apps tell you 🙂
ophelp : This utility lists the available events and short descriptions.

[root@ravi.com ~]# opreport –session-dir=/home/prod/tmpsession
CPU: P4 / Xeon with 2 hyper-threads, speed 2992.73 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
GLOBAL_POWER_E…|
samples|      %|
——————
1109031 51.2560 no-vmlinux
479089 22.1420 libc-2.5.so
207263  9.5791 libperl.so
97973  4.5280 libpython2.4.so.1.0
91993  4.2516 nagios
35979  1.6628 php
35765  1.6529 libz.so.1.2.3
25203  1.1648 ld-2.5.so
21412  0.9896 mysqld
11566  0.5345 libgd.so.2.0.0
10008  0.4625 oprofiled
7661  0.3541 libpthread-2.5.so
6736  0.3113 libnetsnmp.so.10.0.3
5698  0.2633 libpng12.so.0.10.0
4488  0.2074 rateup
3500  0.1618 libcrypto.so.0.9.8e
2138  0.0988 bash
1556  0.0719 libm-2.5.so
1234  0.0570 libmysqlclient.so.15.0.0
606  0.0280 libpcre.so.0.0.1
328  0.0152 mysql.so
316  0.0146 librrd.so.4.1.3
290  0.0134 atop
272  0.0126 sendmail.sendmail
243  0.0112 grep
176  0.0081 nscd
172  0.0079 ping
153  0.0071 nebmodBY0Y2I (deleted)
144  0.0067 libgnutls.so.13.0.6
121  0.0056 init
106  0.0049 gawk

with using symbols you can simply find which apps supporting module takes high load
[root@ravi.com ~]#  opreport –exclude-dependent –symbols –long-filenames –session-dir=/home/prod/tmpsession
CPU: P4 / Xeon with 2 hyper-threads, speed 2992.73 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
samples  %        app name                 symbol name
1109031  51.2560  /no-vmlinux              /no-vmlinux
209506    9.6827  /lib64/libc-2.5.so       _int_free
207263    9.5791  /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/libperl.so /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/libperl.so
97973     4.5280  /usr/lib64/libpython2.4.so.1.0 /usr/lib64/libpython2.4.so.1.0
91993     4.2516  /usr/local/nagios/bin/nagios /usr/local/nagios/bin/nagios
44574     2.0601  /lib64/libc-2.5.so       free
35765     1.6529  /usr/lib64/libz.so.1.2.3 /usr/lib64/libz.so.1.2.3
35032     1.6191  /lib64/libc-2.5.so       vfprintf
22061     1.0196  /lib64/libc-2.5.so       _IO_vfscanf
21412     0.9896  /usr/libexec/mysqld      /usr/libexec/mysqld
16883     0.7803  /lib64/libc-2.5.so       _int_malloc
13631     0.6300  /lib64/libc-2.5.so       memcpy
13165     0.6084  /lib64/libc-2.5.so       _IO_file_xsputn@@GLIBC_2.2.5
1560      0.0721  /lib64/ld-2.5.so         _dl_relocate_object
1462      0.0676  /usr/bin/php             lstep
1385      0.0640  /usr/bin/php             zend_do_fcall_common_helper_SPEC
1258      0.0581  /lib64/libc-2.5.so       rawmemchr
1234      0.0570  /usr/lib64/mysql/libmysqlclient.so.15.0.0 /usr/lib64/mysql/libmysqlclient.so.15.0.0
1226      0.0567  /lib64/libc-2.5.so       realloc
1180      0.0545  /lib64/libc-2.5.so       __tzfile_compute
1156      0.0534  /lib64/ld-2.5.so         check_match.8509
1146      0.0530  /usr/bin/php             _zend_mm_free_int
1084      0.0501  /usr/bin/php             zend_hash_quick_find
1029      0.0476  /lib64/libc-2.5.so       __mpn_mul_1
747       0.0345  /lib64/libc-2.5.so       fgets
738       0.0341  /usr/bin/php             _zval_ptr_dtor

Ref: http://oprofile.sourceforge.net/doc/index.html

-Ravi

(0) Comments    Read More   
Jan
01
Posted on 01-01-2011
Filed Under (General information) by Arun Bagul

Dear All,

We wish you Happy new year 2011 to all of you!

Thank you,
IndianGNU.org

(0) Comments    Read More   

www.flickr.com
arunbagul's photos More of arunbagul's photos
Get Adobe Flash player
-->