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Bug 80819 - Kernel is not handling multiple tasks correctly (not sure its a task problem)
Summary: Kernel is not handling multiple tasks correctly (not sure its a task problem)
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: kernel
Version: 9
Hardware: i386
OS: Linux
Target Milestone: ---
Assignee: Arjan van de Ven
QA Contact: Brian Brock
Depends On:
TreeView+ depends on / blocked
Reported: 2002-12-31 17:58 UTC by Thiago Sayao
Modified: 2008-01-17 17:49 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2004-09-30 15:40:21 UTC

Attachments (Terms of Use)

Description Thiago Sayao 2002-12-31 17:58:17 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021218

Description of problem:
When i copy files from a cd-rom for example all the system gets slow
(maybe an ext3 problem ?). I ran the command top (several times) to see the cpu
utilization and the maximum was 20%. I copied the files with both nautilus and
the command cp and both gives me the same result, everything gets slow. By slow
i mean *very* slow.

My hardware:
 Athlon 1.2Ghz 256mb ram
 52x creative cd-rom
 Hd maxtor 40gb ata 133 (my board is ATA 100)
 Asus A7A133.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Copy files from a not-so-fast media to the root partition.
2. The system will be ***VERY*** slow during the copy.


Additional info:

Comment 1 Nathan G. Grennan 2002-12-31 19:52:20 UTC
Check to see if your cdrom is using DMA with hdparm -d device  RedHat has made
it policy to disable DMA on cdrom drives for compatiability reasons. Which has
the effect of greatly slowing it down for everyone else.

Comment 2 Thiago Sayao 2002-12-31 22:53:20 UTC
[root@zeus sayao]# /sbin/hdparm -d /dev/cdrom
 using_dma    =  1 (on)

Its enabled. 

Comment 3 Thiago Sayao 2003-01-05 00:34:34 UTC
During the boot kernel shows this message:
DMA Disabled

my cd-rom is /dev/hda

Comment 4 Jim Shanks 2003-03-04 18:13:22 UTC
The only way that I have found to reliably switch CD-ROM drives to DMA Mode is to:

su to root
cd /etc/sysconfig
cp harddisks harddiskhda (or harddiskhdb or whatever your CD-ROM is.)

edit the newly created harddiskhda with a text editor and change the USE_DMA=0
to USE_DMA=1.

save the file and restart the machine.

Comment 5 Bugzilla owner 2004-09-30 15:40:21 UTC
Thanks for the bug report. However, Red Hat no longer maintains this version of
the product. Please upgrade to the latest version and open a new bug if the problem

The Fedora Legacy project ( maintains some older releases, 
and if you believe this bug is interesting to them, please report the problem in
the bug tracker at:

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