Re: KVM slow LAMP guest

[Hansa <forums@logic-q.nl>]

On 24-8-2015 1:26, Wanpeng Li wrote:
> On 8/24/15 3:18 AM, Hansa wrote:
>> On 16-7-2015 13:27, Paolo Bonzini wrote:
>>> On 15/07/2015 22:02, "C. Bröcker" wrote:
>>>>> What OS is this?  Is it RHEL/CentOS? If so, halt_poll_ns will be in 6.7
>>>>> which will be out in a few days/weeks.
>>>>>
>>>>> Paolo
>>>> OK. As said CentOS 6.6.
>>>> But where do I put this parameter?
>>> You can add "kvm.halt_poll_ns=500000" to the kernel command line.  If
>>> you have the parameter, you have the
>>> /sys/module/kvm/parameters/halt_poll_ns file.
>> Hi,
>>
>> I upgraded to the CentOS 6.7 release which came out last month and as promised the halt_poll_ns parameter was available.
>> Last week I tested the availability status every 5 minutes on my Wordpress VM's with the halt_poll_ns kernel param set on DOM0. I'm pleased to announce that it solves the problem!
>
> How much seconds to load your Wordpress site this time?
>
> Regards,
> Wanpeng Li
The average is around 0.4 seconds to load my "heaviest" site on my slowest machine.

On the VM server I issued the command below every eleven minutes:

date >>  curltest-file; _
top -b -n 1 | sed -n '7,12p' >> curltest-file; _
curl -o /dev/null -s -w"time_total: %{time_total}\\n" https://my.domain.com | perl -pe 'BEGIN {use POSIX;} print strftime("%Y-%m-%d %H:%M:%S ", localtime)' >> curltest-file

This gives me the total time for displaying my site on a local machine. It also includes a 'top' command to display which processes are running at each sample. All is saved in a file called curltest-file.

I found 7 occurrences in my curltest-file of a time_total larger than 20 seconds. Top however didn't show any significant CPU or IO activity at those sampled times. Further investigations shows me that they are related to a known (gravatar)  issue in the Wordpress Jetpack plugin. I didn't include these samples in the average total.

Cheers and good luck tweaking your sites!
Best, Hansa