From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8117432E152; Thu, 18 Dec 2025 06:00:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766037626; cv=none; b=TeoLCRYYz/yi1YLIydN3xwp7o7/zWK++F4+IrGlPBjk4eXhYAvBdzcZ6IYIR2tG6bI4wwRSYbkAgdJ7hsRmWQaMwYBlNv1Ixrin/ylO7g10RVo46fhRyiy2N3Hb5lYfFTLqK6XbS1Rp0nBcjZan0Yjue5qsRtRNCejqdvaLCbPM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766037626; c=relaxed/simple; bh=PN62smMz9fnkcONiBNdVyrjuDYxkLgyjHAGvxXs6shM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=itHt19CSakalF/3mQYIaj+aRGwh3U/YJephBJuWlCEBfLMFN2Q/9rwE8XIfkJRKR1bhKGVXfRpnov40Y1R1ziZqjFS6QOfoZuHOOL+vcv8cTtvFvfc8mYLb5STLPyLOi5vkehQvc/khmrW0AusKxESKGInzbnG9WBqIjFrLlKc8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=hbYodE/Z; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hbYodE/Z" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=7AZnlHdb5mVs/DWMBb/Fn6vsoTS72x+uWHSaGcyXP+E=; b=hbYodE/Zyf6pmKD15iiGgEvYny URWV0ikQGTiAUqJfk/PSiCb7vNaOYGN2qRdU4jxS2T8CHlQwVPp71BI12BCyF3hG0mVcN1bl899pa hMJgFHu3mXje2KoqVxoYnLDWr8TY7eDe8T4fEe9VkZ+hv4SuNErqi9oS7cGPlFSTgDKZXB/1XBunQ QqL02V3qkCh1mvXYOhIxEqENJSWMKemr48sTstuKC+qPTbAkYNGTRoJHya3q16mnaK2vEdr8Nlpz6 YQQNA08ZkKSJRNlDK8ZUBmdHJRZybItT+Smzvq2zhwqzVxCxN4BjMVCYudQkk8lgfoJv67m5l8CVz CBcBV9pQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vW73n-00000007rvr-3hnF; Thu, 18 Dec 2025 06:00:23 +0000 Date: Wed, 17 Dec 2025 22:00:23 -0800 From: Christoph Hellwig To: Johannes Weiner Cc: Christoph Hellwig , Jens Axboe , Deepanshu Kartikey , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: retiring laptop_mode? was Re: [PATCH] mm: vmscan: always allow writeback during memcg reclaim Message-ID: References: <20251213083639.364539-1-kartikey406@gmail.com> <20251215041200.GB905277@cmpxchg.org> <20251215200838.GC905277@cmpxchg.org> <20251216185201.GH905277@cmpxchg.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: <20251216185201.GH905277@cmpxchg.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Dec 16, 2025 at 01:52:01PM -0500, Johannes Weiner wrote: > On Mon, Dec 15, 2025 at 11:41:07PM -0800, Christoph Hellwig wrote: > > On Mon, Dec 15, 2025 at 03:08:38PM -0500, Johannes Weiner wrote: > > > Debated whether to add some sort of deprecation sysctl handler, but at > > > least systemd-sysctl just prints a warning and still applies other > > > settings from the same config file. > > > > In general dropping sysctl will break things. So I think we'll need > > a stub, at which point it might as well warn for a while. > > Fair enough, I added that. > > Jens, that change seemed small enough that I carried your Ack, but > please let me know if you feel otherwise ;) > > > > Laptop mode was introduced to save battery, by delaying and > > > consolidating writes and maximize the time rotating hard drives > > > wouldn't have to spin. Needless to say, this is a scenario of the > > > (in)glorious past. > > > > Maybe expand on this a bit by mentioning that reclaim now never does > > file system writeback, and fs writeback is already very lumpy by > > design. And of cours that hard disk with their high spinup latency > > and extra power draw are a thing of the past in laptops or other mobile > > devices. > > Sounds good. Can you take a look at the new version below? Looks good: Reviewed-by: Christoph Hellwig