From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (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 CA7783491C8 for ; Fri, 27 Feb 2026 16:43:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772210632; cv=none; b=hX9F/YVfpBYMMeNrdO8pDYFoc1ZOKz/Rd3FUKfluDRuvCnsq/yZ612V8LUqLFp2YWA7Q2Qb+sn4DGM1+oNdovkKlgNs1WBXxkl5i3HDK3WnKRoc41STnLmkif2gAi6GvkZ+xlEzptVHNnqmnKPYtwXcvtxujEVIIlP7hd5PUvSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772210632; c=relaxed/simple; bh=bgEZ6B1UEy/zhpu8n+7s+DafgFxnCJvGv7PZtPNmF9c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mzDtmIwhv0OpTfugl4g/b069HSkMjBVYXRuKRZKXDsteggTyxHp02rJ0ijB3q2VM36KTVpnR1KKOzVn+fyln641in/TbeaNaPBMkUw0ZwuGjOGlbYICwnFSNfCJOfPe3eyqP9qfw/tKXSiGRxixOf4Kw2p9YNrLreWNahLNYEf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=D0WHvJe6; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="D0WHvJe6" Received: from macsyma.thunk.org (pool-173-48-112-142.bstnma.fios.verizon.net [173.48.112.142]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 61RGhJ2g018552 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 27 Feb 2026 11:43:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1772210602; bh=ojcxluCl677xf3TQxwcdPDiL7chtv+USYc/a0Xfg+2c=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=D0WHvJe6noO0P2vihKcQwOmvLodw5oJYzSE+QBqzreFNA0MrcoMFUmRV1v7HYQ7YQ 8VRVBUexRwOsGpeoL5nl7VU0dfJCdDzhi4nPn/ToOtOHDVeWHvmMtSrW/fl17luodM BcVIAYlDVCZbrxeiP3rCuexPD27FmT+QygQUuL+3Jr0pfsRLxits9bH7UQwKaGjUWj snCXSvrABwDEs9B9pSwfveLEzb57UdJy1qulY2XtpE7MJt9f4TEiILm5YOR7gbHWpe JCP/XsTqyUONqwmRUDzv+8sLuu7GrzkKNlfQeOObmaCojX9ExrvTTgSQhp8il92mfX aX5EqNaYHsXwA== Received: by macsyma.thunk.org (Postfix, from userid 15806) id 1ACDD5A2E380; Fri, 27 Feb 2026 11:43:19 -0500 (EST) Date: Fri, 27 Feb 2026 11:43:19 -0500 From: "Theodore Tso" To: Mario Lohajner Cc: Andreas Dilger , libaokun1@huawei.com, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, yangerkun@huawei.com, libaokun9@gmail.com Subject: Re: [PATCH] ext4: rralloc - (former rotalloc) improved round-robin allocation policy Message-ID: <20260227164319.GB93969@macsyma-wired.lan> References: <20260225201520.220071-1-mario_lohajner.ref@rocketmail.com> <20260225201520.220071-1-mario_lohajner@rocketmail.com> <20260226024819.GA39209@macsyma-wired.lan> <04dfeda0-8c13-4233-b631-d8912d4fe6f0@rocketmail.com> <20260227011200.GA68551@macsyma-wired.lan> <2af6328d-5a72-476d-9768-9398a9417ea6@rocketmail.com> 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: <2af6328d-5a72-476d-9768-9398a9417ea6@rocketmail.com> On Fri, Feb 27, 2026 at 03:46:59PM +0100, Mario Lohajner wrote: > > Concentrated allocation can create contention, write amplification, and > uneven LBA utilization even on modern NVMe/SSD devices. Uneven LBA utilization is the thing where I'm asking, "why should we care". In terms of how this would cause contention and write amplification, <>. What is your benchmarks where you can demonstrate this, and how common is this across NVMe/SSD devices? That is, if it's just one trashy product, maybe it should just be avoided --- especially if it has other problems. - Ted