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Old 11-23-2010, 09:32 PM   #1
a_1
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Memory cached & bash problem


Hello.

i have problem when i run this command to ssh to get free ram ,

Code:
echo 3 > /proc/sys/vm/drop_caches
this is code must give me free ram and empty ram cached, i already run this command many time on other nodes i have but with one node when i run this command, i found the ssh hang and can not do any thing , so when i open anther ssh window and type command " top " i see "bash" is take from 89 to 100 % of CPU

i'm try to use kill command like this to stop this bash but can not stop

kill -9 56565
or
killall -9 56565
OR
killall -9 bash

there is nothing need to stop this bash on top using high CPU,


so please if any one can help me ?

Thank you
 
Old 11-23-2010, 09:38 PM   #2
TobiSGD
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It is not needed to "free" RAM this way. If an application needs RAM, the cache will be automatically dropped and the RAM will be assigned to that application. In fact, freeing RAM this way can even decrease performance.
 
Old 11-23-2010, 09:47 PM   #3
a_1
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my nodes used for hosting vpSs and when i need to see the Free -m i see it's like 100 MB only and my node have 16 GB ram , the cached memory is 8 GB . and also the problem now is how to stop/kill this bash on top using all this CPU !!!
 
Old 11-23-2010, 09:48 PM   #4
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Quote:
Originally Posted by a_1 View Post
my nodes used for hosting vpSs and when i need to see the Free -m i see it's like 100 MB only and my node have 16 GB ram , the cached memory is 8 GB .
And that needs to be changed why exactly? :}



Cheers,
Tink
 
Old 11-23-2010, 09:53 PM   #5
a_1
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Originally Posted by Tinkster View Post
And that needs to be changed why exactly? :}



Cheers,
Tink
i'm sorry but i dont know what you mean !
 
Old 11-23-2010, 10:24 PM   #6
catkin
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Quote:
Originally Posted by a_1 View Post
i'm sorry but i dont know what you mean !
Why do you think "my nodes used for hosting vpSs and when i need to see the Free -m i see it's like 100 MB only and my node have 16 GB ram , the cached memory is 8 GB" is a problem?
 
Old 11-23-2010, 10:37 PM   #7
a_1
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Yes problem happend inside vpSs . and it's not problem now to know this info . i'm looking to get help for my orginal post if any one can help me to fix the issue please reply
 
Old 11-23-2010, 10:49 PM   #8
catkin
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Quote:
Originally Posted by a_1 View Post
Yes problem happend inside vpSs . and it's not problem now to know this info . i'm looking to get help for my orginal post if any one can help me to fix the issue please reply
Why do you think it is a problem? Do you know about file system caching as explained on Steve Miller's blog?

EDIT: what Steve Miller doesn't make clear is that unchanged (= not dirty) file system cache pages do not need to be flushed -- the memory they use is available immediately when required for other purposes.

Last edited by catkin; 11-23-2010 at 10:53 PM.
 
Old 11-24-2010, 02:07 AM   #9
a_1
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i'm not talking now about what cach doing i'm talking about how to fix this issue i have
 
Old 11-24-2010, 04:57 AM   #10
TobiSGD
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You wouldn't have an issue if you wouldn't drop the cache, which is an completely unneeded action.
 
Old 11-24-2010, 10:26 AM   #11
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Quote:
Originally Posted by a_1 View Post
i'm not talking now about what cach doing i'm talking about how to fix this issue i have
That's the whole point. You don't actually have an issue; yet
your attempt to fix a non-issue brought you here.
 
Old 11-24-2010, 12:58 PM   #12
a_1
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See the attach file , this day number 3 and i still see this bash take 99% to 100 % kill id not working with this top bash
Attached Thumbnails
Click image for larger version

Name:	bash.JPG
Views:	7
Size:	10.8 KB
ID:	5305  
 
  


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