From: Thomas Lamprecht <t.lamprecht@proxmox.com>
To: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>,
"Proxmox VE development discussion" <pve-devel@lists.proxmox.com>
Subject: Re: [pve-devel] [RFC qemu-server] fix #6935: vmstatus: fallback to RSS in case of KSM usage
Date: Tue, 25 Nov 2025 16:21:23 +0100 [thread overview]
Message-ID: <63ea285f-b56e-4f05-ba2c-f1ac5a0337c6@proxmox.com> (raw)
In-Reply-To: <1764080351.cnbokh9rxb.astroid@yuna.none>
Am 25.11.25 um 15:20 schrieb Fabian Grünbichler:
> On November 25, 2025 3:08 pm, Thomas Lamprecht wrote:
>> Just to be sure: The stats from memory.current or memory.stat inside the
>> /sys/fs/cgroup/qemu.slice/${vmid}.scope/ directory is definitively not
>> enough for our usecases?
>
> well, if we go for RSS they might be, for PSS they are not, since that
> doesn't exist there?
Would need to take a closer look to tell for sure, but from a quick check
it indeed seems to not be there.
> having the live view and the metrics use different semantics seems kinda
> confusing tbh..
more than jumping between metrics over time silently? ;-) The live view can
be easily annotated with a different label or the like if the source is
another, not so easy for metrics.
The more I think about this the more I'm in favor of just deprecating this
again completely, this page table walking can even cause some latency spikes
in the target process, IMO just not worth it. If the kernel can give us this
free, or at least much cheaper, in the future, then great, but until then it's
not really an option. If, we can make this opt-in. The best granularity here
probably would be through guest config, but for starters a cluster-wide
datacenter option could be already enough for the setups that are fine with
this performance trade-off in general.
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next prev parent reply other threads:[~2025-11-25 15:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-25 13:51 Fabian Grünbichler
2025-11-25 14:08 ` Thomas Lamprecht
2025-11-25 14:20 ` Fabian Grünbichler
2025-11-25 15:21 ` Thomas Lamprecht [this message]
2025-11-25 17:21 ` Aaron Lauterer
2025-11-25 18:17 ` Thomas Lamprecht
2025-11-25 14:53 ` Aaron Lauterer
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