Yaniv Dary Technical Product Manager Red Hat Israel Ltd. 34 Jerusalem Road Building A, 4th floor Ra'anana, Israel 4350109 Tel : +972 (9) 7692306 8272306 Email: ydary@redhat.com IRC : ydary On Wed, Feb 22, 2017 at 5:57 PM, Francesco Romani <fromani@redhat.com> wrote:
On 02/21/2017 11:55 PM, Yaniv Dary wrote:
Yaniv Dary Technical Product Manager Red Hat Israel Ltd. 34 Jerusalem Road Building A, 4th floor Ra'anana, Israel 4350109
Tel : +972 (9) 7692306 <+972%209-769-2306> 8272306 Email: ydary@redhat.com IRC : ydary
On Feb 21, 2017 13:06, "Francesco Romani" <fromani@redhat.com> wrote:
Hello everyone,
in the last weeks I've been submitting PRs to collectd upstream, to bring the virt plugin up to date with Vdsm and oVirt needs.
Previously, the collectd virt plugin reported only a subset of metrics oVirt uses.
In current collectd master, the collectd virt plugin provides all the data Vdsm (thus Engine) needs. This means that it is now
possible for Vdsm or Engine to query collectd, not Vdsm/libvirt, and have the same data.
There are only two caveats:
1. it is yet to be seen which version of collectd will ship all those enhancements
2. collectd *intentionally* report metrics as rates, not as absolute values as Vdsm does. This may be one issue in presence of restarts/data loss in the link between collectd and the metrics store.
How does this work? If we want to show memory usage over time for example, we need to have the usage, not the rate. How would this be reported?
I was imprecise, my fault.
Let me retry: collectd intentionally report quite a lot of metrics we care about as rates, not as absolute values. Memory is actually ok fine.
a0/virt/disk_octets-hdc -> rate a0/virt/disk_octets-vda a0/virt/disk_ops-hdc -> rate a0/virt/disk_ops-vda a0/virt/disk_time-hdc -> rate a0/virt/disk_time-vda a0/virt/if_dropped-vnet0 -> rate a0/virt/if_errors-vnet0 -> rate a0/virt/if_octets-vnet0 -> rate a0/virt/if_packets-vnet0 -> rate a0/virt/memory-actual_balloon -> absolute a0/virt/memory-rss -> absolute a0/virt/memory-total -> absolute a0/virt/ps_cputime -> rate a0/virt/total_requests-flush-hdc -> rate a0/virt/total_requests-flush-vda a0/virt/total_time_in_ms-flush-hdc -> rate a0/virt/total_time_in_ms-flush-vda a0/virt/virt_cpu_total -> rate a0/virt/virt_vcpu-0 -> rate a0/virt/virt_vcpu-1
collectd "just" reports the changes since the last sampling. I'm not sure which is the best way to handle that; I've sent a mail to collectd list some time ago, no answer so far.
Can you CC on that thread? I don't know how ES would work with rates at all. I want to be able to show CPU usage over time and I need to know if its 80% or 10%.
-- Francesco Romani Red Hat Engineering Virtualization R & D IRC: fromani