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From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 7158740007 X-Stat-Signature: y4c4yueaipi5qdy3pskbp9tpqz6rrbe5 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1780953581-243703 X-HE-Meta: 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 mUBtj2xM P8pKOFxXUSedNHLQ7x80fq1x4WX3A3XOMK1kzFWkMn/XNggFYCTg0AekNbrSbvt5V03A9TC+K8VA6Gz4yc+iKeatrfR4ljj7WyhB/mahXC+TlrvIGQcs8TYHuA2f12FK79KOwFPUj+Ugce6x6CjWrEG1YGnH7lX0AO0yNLA9TZ2ZuNfsyRaHCdj5qunrszdRS93K9LJckO5HYXY559rNZJ2D/lw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 08/06/2026 20:56, Shakeel Butt wrote: > 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? Yes. How about something like below in the commit message? : This split is the first step toward eventually making vmpressure CONFIG_MEMCG_V1 only. The v2 in-kernel socket pressure path (tree=false) cannot be removed today immediately: PSI is not an exact replacement for vmpressure, and switching networking socket-buffer back-off to PSI may regress networking performance or increase memory pressure in workloads that today rely on vmpressure's hysteresis. The medium-term plan is to introduce a PSI-based socket-pressure path, keep vmpressure available for v2 behind a defconfig as an opt-out for several releases, and only then drop the tree=false path entirely, at which point everything that remains in mm/vmpressure-v1.c is the whole subsystem.