From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from layka.disroot.org (layka.disroot.org [178.21.23.139]) (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 43C7C385522 for ; Fri, 6 Mar 2026 16:44:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.21.23.139 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772815456; cv=none; b=suTKzJqXwEyLuDarpIShUnbi4OTbh5kNNBthqBxExEFAs+DEqgHH/vrqw3VFbpoxKnwgmCsjhUXDcTjyWFrmWHEE/+7oX5V+Z0rttGeE1HGHetk4mYe825AxxlPsi9tKhtanaBc8GAUfalYcuD1PtDgUaMXXRNSSTnlMRhP6AqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772815456; c=relaxed/simple; bh=aiJ6HXP5kCacUDRaAKpFlRAJSn1zFnxlnfcHt7afV9I=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=YF9oxioT+TGsXxvU173/dE4puLFk6k+U+jf4a/8gOqoAXAmSg2SwUCUzuLDAaEe1bOEeRDA4PJyYSSaA4znsIWPDGj1jVlem0b5cr76nIr3j1gyZLFFsFn3aD3zH6PYdVve98DUgfkC+U1eQs6uci3wg61fGkJkZ7w6MiY1h7nc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=disroot.org; spf=pass smtp.mailfrom=disroot.org; dkim=pass (2048-bit key) header.d=disroot.org header.i=@disroot.org header.b=HJoc8+If; arc=none smtp.client-ip=178.21.23.139 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=disroot.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=disroot.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=disroot.org header.i=@disroot.org header.b="HJoc8+If" Received: from [127.0.0.1] (localhost [127.0.0.1]) by disroot.org (Postfix) with ESMTP id C3DB126798; Fri, 6 Mar 2026 17:44:09 +0100 (CET) X-Virus-Scanned: SPAM Filter at disroot.org Received: from layka.disroot.org ([127.0.0.1]) by localhost (disroot.org [127.0.0.1]) (amavis, port 10024) with ESMTP id svw19_WXS9CO; Fri, 6 Mar 2026 17:44:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=disroot.org; s=mail; t=1772815449; bh=aiJ6HXP5kCacUDRaAKpFlRAJSn1zFnxlnfcHt7afV9I=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=HJoc8+IfvN0CgFey940Q7K9ddWRhGHjx/tu5AW/Q+UlbrF0GIGLOeLWEJwBlMEqf7 SP4I8vLfpwRgmAVXtC8s/uDRmzsSk9Hemu3dHgF75CvvGeFBNcrcXnublJyvVuKxfo GrRGrQcFjQ+odUr5Rjkkg2GCojpMCGHhcJ+MWq6r10pW3QNwlQO8jix7lzRh5i0iHq TTHT/pvWfqvvGU2/dtkdzKK5JopVQouRjDhp0MVwtSPaCzJ9JFQfPs00MVWpNQhaDi FWPLrV6hudW1HpsaXd0NAIhkZrkZs9EsBtHgqit7AcZNNOIq/7oOkRvUljG33UB3ao hMfgY0ZP++gaQ== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 06 Mar 2026 17:44:08 +0100 From: Benjamin Lee McQueen To: Michal Hocko 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 In-Reply-To: References: <20260305043038.2176-1-mcq@disroot.org> Message-ID: <31c4680848b833d53b1979b45d5a368d@disroot.org> X-Sender: mcq@disroot.org Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On 2026-03-06 16:52, Michal Hocko wrote: > 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. yes, as i don't personally have a workload that explicitly requires vmpresssure to not generate bogus events, it is still technically a "bug" that can still be improved. i believe many legacy systems would benefit from this as they still use vmpressure notifications. i agree PSI is the preferred interface, but vmpressure is still used in other production environments, like Android's LMKD, right? -ben