From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 50DD5281503 for ; Fri, 6 Mar 2026 15:52:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772812371; cv=none; b=abR+iSPEsf8m92u2dEYoFubxPfRVpIf3KPPLUWtIhw0kYjS7T3DO7sFCAkJWhrBoDTx9Je0aOACiquIR8ApyMMn+a49vdwvH5E7vzJH4gnqHLkQy/kuYN6Lw8s4+b+4D0wniRbrvac8n7LS5dA88l0OixleW8E0vM12Xc3/Ep9A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772812371; c=relaxed/simple; bh=trLVCQrTsS+UHmeuvD7Vhmhc3wJkHqQ2wKYIv6d6YiE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cg1nkQPeh4ZaSPM5NvnTLlg2hCpnKOfEWu76feARzqc8u24tTu1yFkURo8+vl7hnXZ+lG3b2I93p/HgUm/l8kZhhXFC9vsAEkTIYqEOADXHoCCZFFm72ADQsYtbFX+FAU9IyNU8kv8515Q9X0MrNckUMjvRDHk3HtWdeuaMD2kI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=VC6RuOzf; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="VC6RuOzf" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-482f454be5bso96367015e9.0 for ; Fri, 06 Mar 2026 07:52:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1772812368; x=1773417168; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=gmR7x9X/+WhBljqVLIwDH2yaruypUaKc2mU2QgggGQw=; b=VC6RuOzfIhZFdFv//rz/zuYNmxpQSlk+eQG5CHVJPuf87zsG17HMtjcXQqWDoyMRE3 hURdVEBAvb2Sv1HXvxbydlTavBeZc5x5IU6jUvHbMCuU1eHRoT6XGN5aotlNsinKYu9u 8Ioih6uwmZJNKmidhyhT6ivFjl/UBILzzLNQKOqugYKbdLUjmQnR+onsLVBQoIblBlbD jRxHeejRftxoPlL1h8AgtkQDaDnIPVywR5XdAgtcsGspvqaXmsg+YdttX7bahKn6cx0j uorlg7vmjv/yizZUp2wN2icP+ehBGb2li9NWTZlj71xVDDjx2ztohmHTmaZyFsQ411+6 owog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772812369; x=1773417169; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gmR7x9X/+WhBljqVLIwDH2yaruypUaKc2mU2QgggGQw=; b=dWkdNX7o/40fGFbM3DFbkchi1MY4zivsolBdk0P9XrrDbPU3qtR0IKPDRvzwcNNZdQ +/8fmSp46p3cuD/IqInY/AxwNbcL1DYfrNGmnWtDM2enSBZThSwh6uZWONN3ODd+eFWP XZnnmspE/nS5Ow21Y8QXQQ4Z5BdWZ8hpPYRgYJFiEMHJdTd4crRLzs3pVldvfayShfjD ul3QIe2/FeMsk8qPa/1f2BuAvXG8WmOxHm0PC/EC1s7o3MU6hdONdUiKMCRADOO6tlFu yeYeV6NwQ9ruUbj2i81h6MMX11af+cn4NxUEIVp3fPueLb+RugMlxSWeueHJ+lc3hhvO wnAg== X-Forwarded-Encrypted: i=1; AJvYcCWJ9tkLCg1utzONerodNfnC4qixPWfVg2Ne6Xxddugj3ga/ExQomQXERlU/LifO9gZWZCANz5UVa4JWawY=@vger.kernel.org X-Gm-Message-State: AOJu0Ywc5oTY2Wd8cnXZ9nO/G+qmPSXiumM8WdxUR0VOCJbHnsk7FTf6 P1iwIfVFeTk7tXiAkuRRFzaKei98QOFAjVXGGHN2/4J1sPjCtF/XAZKrlp7b10Q6xKg= X-Gm-Gg: ATEYQzyvhQsesSoG3O5fvv96imlOqINLz/T1dCT7dQhfsY2birXpsBn4TPt2BVKKZBO ATI9j0Usddfw8YJxG7Vr/G25EP7y2G13wuuOBrZGBK0nEBzZhwLjVv33k2OQ5x3QWX+/+EvEGqV 4yqG8owQdusgXtWsRjDyBn5G9uAdaGSgmfsreWg9RG2V5Nfxe/as3ZesL89Wx4SzUrB3z1lKnAP qgSaY/H92yLslA8yGa98UgePFoA0gq85O8MXan86x6hPwQOzQP+51Sts11C2aCcsLDPmdM3h0uc HlC9rpPAr/QVvM0Aj9cCBYkNIpzq00GLu5yenKToaR4+2svY7bNzhRoEA2E9XjcX4FBdPLYYP1f 5wCdn4CpSQ5YVysRKUPwFOo7ssVkThRQpz5jZNFC5YszFDG3A0kPczQTy6w4zPbdtYcNVbqtwz4 mOKJYODyirD9M340Cj0mPIaTEmp4yS5sEa0Q== X-Received: by 2002:a05:600c:3e10:b0:480:4a90:1afd with SMTP id 5b1f17b1804b1-485264e7588mr42095305e9.0.1772812368602; Fri, 06 Mar 2026 07:52:48 -0800 (PST) Received: from localhost (109-81-88-63.rct.o2.cz. [109.81.88.63]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-439dae4b860sm5074257f8f.36.2026.03.06.07.52.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Mar 2026 07:52:48 -0800 (PST) Date: Fri, 6 Mar 2026 16:52:47 +0100 From: Michal Hocko To: Benjamin Lee McQueen Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3] mm/vmpressure: scale window size based on machine memory Message-ID: References: <20260305043038.2176-1-mcq@disroot.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260305043038.2176-1-mcq@disroot.org> On Wed 04-03-26 22:30:38, Benjamin Lee McQueen wrote: > the vmpressure window size has been fixed at 512 pages > (SWAP_CLUSTER_MAX * 16), ever since the file's inception. a TODO in > the file notes that the vmpressure window size should be scaled > similarly to vmstat's scaling, via machine size. > > the problem with fixed window size on large memory systems: Thank you for this much more detail insight into your thinking. This is a good start. I am still missing an overall motivation though. Are you trying to address a theoretical concern (the said TODO) or do you have any practical workload that generates bogus vmpressure events. Also please note that vmpressure is a legacy notification interface only available in cgroup v1. PSI (via memory.pressure or global /proc/pressure/) is a new/preferred method to measure memory pressure. See more Documentation/accounting/psi.rst -- Michal Hocko SUSE Labs