[Netkit.users] First official release of Netkit-NG
Saverio Proto
zioproto at gmail.com
Fri Jun 13 14:54:27 CEST 2014
Hello,
sorry, noatime was not really solving the problem :( It was a false positive.
The problem is the access from the host machine to the netkit
filesystem, when the UML machine is doing disk intesive operations.
There are some operations that cause the journaling of the host file
system to get all the IO resources.
To check the worst case just do
vstart nuovo -M 512 --eth0=tap,172.17.0.1,172.17.0.2 -W
set a nameserver in /etc/resolv.conf and try "apt-get update"
in my case the UML system hangs for more than 4 minutes on "Reading
package lists".
To make sure it is filesystem related I did this test, I moved the
netkit-fs to a ramdisk.
Doing the same:
vstart nuovo -M 512 --eth0=tap,172.17.0.1,172.17.0.2 -W
apt-get update (in the UML machine)
this is now SUPER fast.
I append here my bash history.
Saverio
2088 sudo mount -t tmpfs -o size=2512M tmpfs /mnt/ramdisk
2089 cd
2090 rm netkit-ng/fs/netkit-fs-i386-F7.0
2091 tar -jxvf ~/Scaricati/netkit-ng-filesystem-i386-F7.0.tar.bz2
2092 cp netkit-ng/fs/netkit-fs-i386-F7.0 /mnt/ramdisk/
2093 cd netkit-ng/fs/
2094 ls -alh
2095 rm netkit-fs
2096 ln -s /mnt/ramdisk/netkit-fs-i386-F7.0 netkit-fs
2097 ls -alh
2098 cd
2099 cd /tmp/
2100 vstart nuovo -M 512 --eth0=tap,172.17.0.1,172.17.0.2 -W
2014-06-13 14:18 GMT+02:00 Julien Iguchi-Cartigny
<julien.iguchi-cartigny a lifl.fr>:
> On 06/13/2014 02:16 PM, Saverio Proto wrote:
>> I found the problem.
>>
>> http://tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/chap6sec73.html
>>
>> my home partition is NOT mounted with noatime
>>
>> I just tried
>>
>> chattr +A netkit-fs-i386-F7.0
>>
>> saverio a nockid:~/netkit-ng/fs$ lsattr netkit-fs-i386-F7.0
>> -------A-----e- netkit-fs-i386-F7.0
>> saverio a nockid:~/netkit-ng/fs$
>>
>>
>> I started a machine with -W (Cow mode) and it is very fast now.
>>
>> I will make more detailed tests later, but this looks like to be the problem.
>
> Ok I'm waiting your feedback then I will write a new test in check
> configuration to avoid it again.
>
> Thanks again for your precious help.
>
> Julien
>
>> Saverio
>>
>>
>>
>> 2014-06-13 14:03 GMT+02:00 Saverio Proto <zioproto a gmail.com>:
>>> I mean jbd2 is taking IO time on the host machine.
>>>
>>> Saverio
>>>
>>>
>>> 2014-06-13 13:10 GMT+02:00 Julien Iguchi-Cartigny
>>> <julien.iguchi-cartigny a lifl.fr>:
>>>> On 06/13/2014 01:07 PM, Saverio Proto wrote:
>>>>> Using iotop I see that the process that consumes all the IO time when
>>>>> the UML machines are very slow is:
>>>>>
>>>>> jbd2/sdb1-8
>>>>
>>>> jbd2 is now used (it is a fs system). I will try to build new images
>>>> this WE without it.
>>>>
>>>> Thanks for your feedback.
>>>>
>>>> J.
>>>>
>>>>
>>>>> I have this process using 99.99% IO time
>>>>>
>>>>> This is when the UML kernel needs to perform a disk write operation
>>>>>
>>>>> Saverio
>>>>>
>>>>>
>>>>> 2014-06-13 13:01 GMT+02:00 Saverio Proto <zioproto a gmail.com>:
>>>>>>> Could you precise if it's the I/O or the CPU use which seems slow ?
>>>>>>
>>>>>> Hello,
>>>>>> it is I/O problem. CPU is running low.
>>>>>>
>>>>>>> Could you describe your test computer architecture (32/64 bits ?
>>>>>>> distribution ?) ?
>>>>>>
>>>>>> saverio a nockid:~$ cat /etc/issue
>>>>>> Ubuntu 12.04.4 LTS \n \l
>>>>>>
>>>>>> saverio a nockid:~$ uname -a
>>>>>> Linux nockid 3.2.0-58-generic #88-Ubuntu SMP Tue Dec 3 17:37:58 UTC
>>>>>> 2013 x86_64 x86_64 x86_64 GNU/Linux
>>>>>> saverio a nockid:~$ cat /proc/cpuinfo | head
>>>>>> processor : 0
>>>>>> vendor_id : GenuineIntel
>>>>>> cpu family : 6
>>>>>> model : 42
>>>>>> model name : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
>>>>>> stepping : 7
>>>>>> microcode : 0x17
>>>>>> cpu MHz : 2400.000
>>>>>> cache size : 8192 KB
>>>>>> physical id : 0
>>>>>> saverio a nockid:~$
>>>>> _______________________________________________
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