Re: [pve-devel] [PATCH pve-common 1/1] ProcFSTools: add read_pressure

[Alexandre Derumier <aderumier@odiso.com>]

>>Why do you need 10s resulution? Isn't 1min good enough?
Well, if the 1min is an average of 10s metric, it's ok.

I'm currently using 1min average and 5min average, so it's not a problem
with current rrds.

Thanks for the informations !


(I'll resend a patch to add pressure to rrd, and also add vm/ct pressure)


Le mar. 13 oct. 2020 à 09:38, Dietmar Maurer <dietmar@proxmox.com> a écrit :

> > BTW, I'm currently playing with reading the rrd files, and I have notice
> than lower precision is 1minute.
> > as pvestatd send values around each 10s, is this 1minute precision an
> average of 6x10s values send by pvestatd ?
>
> Yes (we also store the MAX)
>
> > I'm currently working on a poc of vm balancing, but I would like to have
> something like 15min of 10s precision (90 samples of 10s).
>
> Why do you need 10s resulution? Isn't 1min good enough?
>
> > So currently I'm getting stats each 10s manually
> with PVE::API2Tools::extract_vm_stats like the ressource api.
> > (This use PVE::Cluster::rrd_dump , but I don't understand the ipcc_.
> code. does it only return current streamed values?
> > then after the rrdcached daemon is writing to rrd file the average
> values each minute ?)
> >
> > I don't known if we could have rrd files with 15min of 10s precision ?
> (don't known the write load impact on disks)
>
> We use the following RRD conf, step is 60 seconds (see
> pve-cluster/src/status.c):
>
> static const char *rrd_def_node[] = {
>         "DS:loadavg:GAUGE:120:0:U",
>         "DS:maxcpu:GAUGE:120:0:U",
>         "DS:cpu:GAUGE:120:0:U",
>         "DS:iowait:GAUGE:120:0:U",
>         "DS:memtotal:GAUGE:120:0:U",
>         "DS:memused:GAUGE:120:0:U",
>         "DS:swaptotal:GAUGE:120:0:U",
>         "DS:swapused:GAUGE:120:0:U",
>         "DS:roottotal:GAUGE:120:0:U",
>         "DS:rootused:GAUGE:120:0:U",
>         "DS:netin:DERIVE:120:0:U",
>         "DS:netout:DERIVE:120:0:U",
>
>         "RRA:AVERAGE:0.5:1:70", // 1 min avg - one hour
>         "RRA:AVERAGE:0.5:30:70", // 30 min avg - one day
>         "RRA:AVERAGE:0.5:180:70", // 3 hour avg - one week
>         "RRA:AVERAGE:0.5:720:70", // 12 hour avg - one month
>         "RRA:AVERAGE:0.5:10080:70", // 7 day avg - ony year
>
>         "RRA:MAX:0.5:1:70", // 1 min max - one hour
>         "RRA:MAX:0.5:30:70", // 30 min max - one day
>         "RRA:MAX:0.5:180:70",  // 3 hour max - one week
>         "RRA:MAX:0.5:720:70", // 12 hour max - one month
>         "RRA:MAX:0.5:10080:70", // 7 day max - ony year
>         NULL,
> };
>
> Also See: man rrdcreate
>
> So no, you do not get 10s precission from RRD.
>
>