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From: Shakeel Butt To: Usama Arif Cc: Andrew Morton , david@kernel.org, linux-mm@kvack.org, hannes@cmpxchg.org, tj@kernel.org, mkoutny@suse.com, roman.gushchin@linux.dev, liam@infradead.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, kernel-team@meta.com Subject: Re: [PATCH 0/2] mm/vmpressure: reduce CPU, memory and code overhead on cgroup v2 Message-ID: References: <20260606114158.3126210-1-usama.arif@linux.dev> <750406a5-1819-4ca6-81d8-5a1d82e0644b@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <750406a5-1819-4ca6-81d8-5a1d82e0644b@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: ig99d8e6zihfedwarcjzfmnicsn1bghw X-Rspamd-Queue-Id: E99C4100009 X-HE-Tag: 1780948618-400601 X-HE-Meta: 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 g53poQXR iklK1/KPcck7ngJwD4xADVOXUfGIPCnSXDwkZkUclDEZb4RNRDrACV4lUNfZBAZ+vi6E/YOXiIEeMGfcWqdMGFXHoadJlh4As9RQa9iZvbmNkMYrXc8fm8U7b/Oc/een3Tvgco2P/nB9u6KlGm9G4K1nfGdTe2YiF3fdaAgv2w4yIGP7K5/OUMRcE5rhhYt9TUJ+b89jrPe2fO4Ihca8fcogEIA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 08, 2026 at 07:49:45PM +0100, Usama Arif wrote: > > > > > > For this, I am wondering if we should just go ahead and work towards making > > vmpressure memcg-v1 only unless we foresee a lot of or complex work is needed > > for that and only then patch 2 makes sense. > > > > I think there might be a transition needed? Because vmpressure and PSI > do not work out to be the same and people might notice a regression with > increased memory usage or a hit in networking performance and might want to > opt out? A solution might be to switch socket pressure to PSI while > keeping vmpressure around gated by a defconfig. And then in a few releases > remove it completely for cgroup v2 if no one complaints. If we go down that > path, we would need patch 2 for the medium term. Yeah the reasoning that PSI is not an exact replacement for vmpressure makes sense and it will take couple of iterations to transition v2 (networking) away from vmpressure. Can you please update your commit message with this and about the midterm or transition plan. I assume eventually we will just have vmpressure-v1.c file which will be behind MEMCG_V1 flag, correct?