Re: KVM slow LAMP guest

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On 8/25/15 11:42 PM, Hansa wrote:
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.

Nice!


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.

If you just use halt_poll_ns or both halt_poll_ns and idle=poll in guest?

Regards,
Wanpeng Li


Cheers and good luck tweaking your sites!
Best, Hansa
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