netdev - Re: [PATCH v3] memcg: expose socket memory pressure in a cgroup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <irvyenjca4czrxfew4c7nc23luo5ybgdw3lquq7aoadmhmfu6h@h4mx532ls26h>
Date: Wed, 23 Jul 2025 10:54:11 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Daniel Sedlak <daniel.sedlak@...77.com>
Cc: Michal Koutný <mkoutny@...e.com>, 
	Kuniyuki Iwashima <kuniyu@...gle.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Jonathan Corbet <corbet@....net>, Neal Cardwell <ncardwell@...gle.com>, 
	David Ahern <dsahern@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>, linux-mm@...ck.org, netdev@...r.kernel.org, 
	Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Muchun Song <muchun.song@...ux.dev>, cgroups@...r.kernel.org, 
	Matyas Hurtik <matyas.hurtik@...77.com>
Subject: Re: [PATCH v3] memcg: expose socket memory pressure in a cgroup

On Wed, Jul 23, 2025 at 10:58:10AM +0200, Daniel Sedlak wrote:
> On 7/23/25 10:38 AM, Michal Koutný wrote:
> > On Tue, Jul 22, 2025 at 01:11:05PM -0700, Shakeel Butt <shakeel.butt@...ux.dev> wrote:
> > > > > 1 second is the current implementation and it can be more if the memcg
> > > > > remains in memory pressure. Regarding usefullness I think the periodic
> > > > > stat collectors (like cadvisor or Google's internal borglet+rumbo) would
> > > > > be interested in scraping this interface.
> > > > 
> > > > I think the cumulative counter suggested above is better at least.
> > > 
> > > It is tied to the underlying implementation. If we decide to use, for
> > > example, PSI in future, what should this interface show?
> > 
> > Actually, if it was exposed as cummulative time under pressure (not
> > cummulative events), that's quite similar to PSI.
> 
> I think overall the cumulative counter is better than just signaling 1 or 0,
> but it lacks the time information (if not scraped periodically). In
> addition, it may oscillate between under_pressure=true/false rather quickly
> so the cumulative counter would catch this.

Yes cumulative counter would not miss small bursts.

> 
> To me, introducing the new PSI for sockets (like for CPU, IO, memory), would
> be slightly better than cumulative counter because PSI can have the timing
> information without frequent periodic scrapes. So it may help with live
> debugs.

How would this PSI for sockets work? What would be the entry and exit
points?

> 
> However, if we were to just add a new counter to the memory.stat in each
> cgroup, then it would be easier to do so?