From: Alexandre Derumier <aderumier@odiso.com>
To: Dietmar Maurer <dietmar@proxmox.com>
Cc: Proxmox VE development discussion <pve-devel@lists.proxmox.com>
Subject: Re: [pve-devel] [PATCH pve-common 1/1] ProcFSTools: add read_pressure
Date: Tue, 13 Oct 2020 08:32:50 +0200 [thread overview]
Message-ID: <CAMGxVzBo940=kdAHLxWgY6RkuFYnHxwP-pEexs_rw8zSegogLA@mail.gmail.com> (raw)
In-Reply-To: <190420382.634.1602569100580@webmail.proxmox.com>
>>I have no idea how reliable this is, because we do not use cgroups v2.
But yes,
>>I think this would be useful.
I have tested it on a host with a lot of small vms. (something like 400vms
on a 48cores), with this number of vms, they was a lot of context
switches, and vms was laggy.
cpu usage was ok (maybe 40%), loadaverage was around 40, but pressure was
around 20%. (so it seem more precise than loadaverage)
global /proc/pressure/cpu was almost the sum of cgroups of
/sys/fs/cgroup/unified/qemu.slice/<vmid>.scope/cpu.pressure
so,it seem reliable.
(I don't have lxc container in production, but I think it should be the
same)
So, yes, I think we could add them to rrd for both host/vms.
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 ?
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).
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)
Le mar. 13 oct. 2020 à 08:05, Dietmar Maurer <dietmar@proxmox.com> a écrit :
> > I have notice that it's possible to get pressure info for each vm/ct
> > through cgroups
> >
> > /sys/fs/cgroup/unified/qemu.slice/<vmid>.scope/cpu.pressure
> > /sys/fs/cgroup/unified/lxc/<vmid>/cpu.pressure
> >
> >
> > Maybe it could be great to have some new rrd graphs for each vm/ct ?
> > They are very useful counters to known a specific vm/ct is overloaded
>
> I have no idea how reliable this is, because we do not use cgroups v2. But
> yes,
> I think this would be useful.
>
>
next prev parent reply other threads:[~2020-10-13 6:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-06 11:58 [pve-devel] [PATCH pve-common 0/1] " Alexandre Derumier
2020-10-06 11:58 ` [pve-devel] [PATCH pve-common 1/1] " Alexandre Derumier
2020-10-11 8:23 ` Alexandre Derumier
2020-10-13 6:05 ` Dietmar Maurer
2020-10-13 6:32 ` Alexandre Derumier [this message]
2020-10-13 7:38 ` Dietmar Maurer
2020-10-13 12:05 ` Alexandre Derumier
2020-10-13 5:35 ` [pve-devel] applied: " Dietmar Maurer
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