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 885A9136351 for ; Wed, 3 Dec 2025 06:31:22 +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=1764743486; cv=none; b=cN9JwAHo9STalhjQtlH7mZdVAnyy2mrXlUVoXN+VjDhqheGiTu0ocaLLfRSMyr5VfELzpVd4kamX+se+IeNJDGrZabFsp5BJ7wFhGqw1f0LxCsejIjiWJr1Vs/NhViSE+8V/vTbBOMvILn3w/e44wAKTA+fseEtzvnOTZPHNSEQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764743486; c=relaxed/simple; bh=6qpH4pN+X/nozQgrFEUiRSAM2JRrdturru6xYwZgNl4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Gw+JMekiTvEMRNo0ODKzlhJ07vW3CxRaZ+7mFB4H05rvk3WfdE1Zq1T0Ai6NBZzXKiVWZZA+dVaYmiZ/vQcvJ2qLChpz6ScxX+cCRGuLoUcna00SnEDeRnDgpCgRbBuHRw2NfPMecpoDwzBl2Ja7LUGSf5ThLUR0BGX8ZCRSvRg= 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=qInjLbGe; 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="qInjLbGe" 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=9MBfFYsHuMrnuzRQjJTGICwra3mloX0fAtre0MPW5Us=; b=qInjLbGehnqboWwaAl+qLeVQ1E 135pW9iNX/xXIAuf0XmHaMhPeVeRJPrnXVvYhZcWbn4bAjas518QC8wNebKe0Cie/J5S3OHDWqnek d8i05kLramfro1XghR1harn/yEc47i09C8tZOziJI1dEYQlFOjVTPsUPk90fUz5k5v0coD6dLtNz6 2GZxP4uYlnqF1G8xCTG2gh3mPHZDouR2LJSz4ffPh3DfgSlEa7Jq+eLkXKFr0ra39+6WVqyo3/K9w GUuKWk9pLXWZtf/r9RU5XzyZWodnGMZHBS+4KD04EWYW/qcBm70UR56bUFpgom7XcyQGVtD9bTaeH EAO9I4gA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQgOY-00000006Bri-08ZI; Wed, 03 Dec 2025 06:31:22 +0000 Date: Tue, 2 Dec 2025 22:31:22 -0800 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , aalbersh@kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH 1/2] mkfs: enable new features by default Message-ID: References: <176463876373.839908.10273510618759502417.stgit@frogsfrogsfrogs> <176463876397.839908.4080899024281714980.stgit@frogsfrogsfrogs> <20251203005345.GD89492@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-xfs@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: <20251203005345.GD89492@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Dec 02, 2025 at 04:53:45PM -0800, Darrick J. Wong wrote: > On Mon, Dec 01, 2025 at 11:38:46PM -0800, Christoph Hellwig wrote: > > On Mon, Dec 01, 2025 at 05:28:16PM -0800, Darrick J. Wong wrote: > > > From: Darrick J. Wong > > > > > > Since the LTS is coming up, enable parent pointers and exchange-range by > > > default for all users. Also fix up an out of date comment. > > > > Do you have any numbers that show the overhead or non-overhead of > > enabling rmap? It will increase the amount of metadata written quite > > a bit. > > I'm assuming you're interested in the overhead of *parent pointers* and > not rmap since we turned on rmap by default back in 2023? Yes, sorry. > I see more or less the same timings for the nine subsequent runs for > each parent= setting. I think it's safe to say the overhead ranges > between negligible and 10% on a cold new filesystem. Should we document this cleary? Because this means at least some workloads are going to see a performance decrease.