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Old 11-05-2010, 10:24 AM   #1
hiteurecomupf
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Kernel Panic: not syncing: VFS: Unable to mount root fs on unknown block (0,0)


Hi All ,

I am facing this Linux Kernel non compilation problem.I am running Ubuntu 9.10 Kernel 2.6.31-22-generic. Now i have changed 2 things in the kernel configurations. First is the kernel frequency from 250 Hz to 1000 Hz and Secondly the UDP_HTABLE_SIZE from 128 to 32768. This both the changes are needed for testing my IMS Bench SIPp load generator for generating huge number of user loads for my OpenIMSCore simulation environement. Now after making both the changes and following the exact rules , http://ubuntuforums.org/showthread.php?t=43065 , and after making all the changes when i am rebooting the OS , i am getting the error , "Kernel Panic: not syncing: VFS: Unable to mount root fs on unknown block (0,0).."

Can any one suggest me how to resolve this issue.

Regards ,

Sougata
 
Old 11-05-2010, 02:24 PM   #2
nini09
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Is there kernel panic if you don't apply UDP_HTABLE_SIZE change?
 
Old 11-08-2010, 04:27 AM   #3
hiteurecomupf
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Hi ,

Well i have changed both the values at the same time.
Both the values , Kernel Timer Frequency(changed to 1000 Hz) and UDP_HTABLE_SIZE(changed to 32768) have been done at the same time and then i recompiled the kernel.

Regards ,

Sougata
 
Old 11-08-2010, 08:19 AM   #4
hiteurecomupf
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Hi All ,

I guess the Kernel Panick is coming due to the change of the UDP_HTABLE_SIZE. Now my kernel is Ubuntu 9.10 Karmic with 9.10 Kernel 2.6.31-22-generic. The value of the UDP_HTABLE_SIZE was 128 which i changed. The reason for this change is, the system will generate UDP traffic for 1,00,000 users which i need to evaluate and test. You can refer to this webpage of the traffic load generator which i will be using , http://sipp.sourceforge.net/ims_benc...Pre-requisites.

NOw my question is , what can be the value for this UDP_HTABLE_SIZE constant? Is 128 is fixed or can i increase this value to any optimum level?If yes then what can be the value i can increase and re compile the kernel so that this panic error doesn't come any more?

Regards ,

Sougata
 
Old 11-08-2010, 03:43 PM   #5
nini09
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What's your CPU word width, 32 or 64 bits?
 
Old 11-09-2010, 08:50 AM   #6
hiteurecomupf
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CPU word width is 64 bits.
Cheers ,
Sougata
 
Old 11-09-2010, 02:28 PM   #7
nini09
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Try to set UDP_HTABLE_SIZE to 8096.
 
  


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