Re: Centos 6.9 and centos 7

To make a better testing, I used a third server.
This is identical to the centos 7 machine, and it is not included in the
replica cluster.

Nobody is accessing this machine, this is top :

top - 14:48:36 up 73 days, 17:39, 3 users, load average: 0.00, 0.01, 0.05
Tasks: 686 total, 1 running, 685 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si,
0.0 st
KiB Mem : 26383592+total, 1782196 free, 2731144 used, 25932257+buff/cache
KiB Swap: 16777212 total, 16298536 free, 478676 used. 21693456+avail Mem

These are timings :
Time: 2.841 ms
Time: 1.980 ms
Time: 2.240 ms
Time: 2.947 ms
Time: 2.828 ms
Time: 2.227 ms
Time: 1.998 ms
Time: 1.990 ms
Time: 2.643 ms
Time: 2.143 ms
Time: 2.919 ms
Time: 2.246 ms

I never got same results of the centos 6.9 machine.

2017-12-04 15:40 GMT+01:00 Nicola Contu <nicola(dot)contu(at)gmail(dot)com>:

> These are the timings in centos 7 :
>
> Time: 4.248 ms
> Time: 2.983 ms
> Time: 3.027 ms
> Time: 3.298 ms
> Time: 4.420 ms
> Time: 2.599 ms
> Time: 2.555 ms
> Time: 3.008 ms
> Time: 6.220 ms
> Time: 4.275 ms
> Time: 2.841 ms
> Time: 3.699 ms
> Time: 3.387 ms
>
>
> These are the timings in centos 6:
> Time: 1.722 ms
> Time: 1.670 ms
> Time: 1.843 ms
> Time: 1.823 ms
> Time: 1.723 ms
> Time: 1.724 ms
> Time: 1.747 ms
> Time: 1.734 ms
> Time: 1.764 ms
> Time: 1.622 ms
>
>
> This is top on centos 6 :
>
> [root(at)****]# top
> top - 14:33:32 up 577 days, 23:08, 1 user, load average: 0.16, 0.11, 0.15
> Tasks: 1119 total, 1 running, 1118 sleeping, 0 stopped, 0 zombie
> Cpu(s): 0.0%us, 0.1%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si,
> 0.0%st
> Mem: 132040132k total, 129530504k used, 2509628k free, 108084k buffers
> Swap: 11665404k total, 331404k used, 11334000k free, 124508916k cached
>
> This is top on centos 7:
>
> top - 14:35:38 up 73 days, 19:00, 6 users, load average: 22.46, 20.89,
> 20.54
> Tasks: 821 total, 13 running, 807 sleeping, 0 stopped, 1 zombie
> %Cpu(s): 14.2 us, 5.0 sy, 0.0 ni, 77.5 id, 3.1 wa, 0.0 hi, 0.2 si,
> 0.0 st
> KiB Mem : 26383592+total, 4301464 free, 6250384 used, 25328406+buff/cache
> KiB Swap: 16777212 total, 11798876 free, 4978336 used. 24497036+avail Mem
>
>
> The production machine is obviously more accessed. But that does not seem
> to be the problem as running the same query on the replica of the
> production machine (same config of the master but not accessed by anyone)
> gives the same bad result:
> Time: 6.366 ms
>
>
> 2017-12-04 15:19 GMT+01:00 Chris Mair <chris(at)1006(dot)org>:
>
>> centos 7 :
>>> Time: 3.884 ms
>>>
>>> centos 6.9
>>>
>> Time: 1.620 ms
>>
>>>
>>>
>>> Is there anything you can advice to solve or identify the problem?
>>>
>>
>> Can you run this query 10 times on each server and note the timings?
>>
>> I'd like to see the reproducability of this.
>>
>> Also: both machines are otherwise idle (check with top or uptime)?
>>
>> Bye,
>> Chris.
>>
>>
>>
>