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 B80F12F432E for ; Thu, 26 Jun 2025 14:57:43 +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=1750949865; cv=none; b=abobgoaNlKa3f3PRbjGn8SRlIIwt8WRCL6+7SVWpWHtPVMHJHfTR5A5dFNP7gjEHlTUCED0GIkue3QPM6TOhUZVZcMsxutX3A8uY4Nckz2VrkT73eVkF3kQukwWK/wW9Kn4GZtIH4jlTVwSr6+lPpZQMYLVlvYWr4hz6eTXsrLI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750949865; c=relaxed/simple; bh=ztsrZ2ghDkkt7vjAj7/2MBmD+lpdTjfpFkNsL0ZFcYc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A1FgxgMyOuHfTJmPozvfsJwa3RDWB7k6m7APFdSZrVQR95MXnTMkD7dGSigQwDFxc2SllibdIxB+WlLVdpTD/ndgmgP9EKytLRXzaIxmySjltdDwhBYiyJOTVW9kCZ96i3vRRR6fzrElrkJzch04P98RAgwc4A4EGEr7YghUGhk= 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; 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 Received: from trampoline.thunk.org (pool-173-48-82-219.bstnma.fios.verizon.net [173.48.82.219]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 55QEumDf013726 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 26 Jun 2025 10:56:48 -0400 Received: by trampoline.thunk.org (Postfix, from userid 15806) id DD0352E00D5; Thu, 26 Jun 2025 10:56:47 -0400 (EDT) Date: Thu, 26 Jun 2025 10:56:47 -0400 From: "Theodore Ts'o" To: Zhang Yi Cc: "D, Suneeth" , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, adilger.kernel@dilger.ca, jack@suse.cz, yi.zhang@huawei.com, libaokun1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com Subject: Re: [PATCH v2 8/8] ext4: enable large folio for regular file Message-ID: <20250626145647.GA217371@mit.edu> References: <20250512063319.3539411-1-yi.zhang@huaweicloud.com> <20250512063319.3539411-9-yi.zhang@huaweicloud.com> <94de227e-23c1-4089-b99c-e8fc0beae5da@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <94de227e-23c1-4089-b99c-e8fc0beae5da@huaweicloud.com> On Thu, Jun 26, 2025 at 09:26:41PM +0800, Zhang Yi wrote: > > Thanks for the report, I will try to reproduce this performance regression on > my machine and find out what caused this regression. I took a quick look at this, and I *think* it's because lmbench is measuring the latency of mmap read's --- I'm going to guess 4k random page faults, but I'm not sure. If that's the case, this may just be a natural result of using large folios, and the tradeoff of optimizing for large reads versus small page faults. But if you could take a closer look, that would be great, thanks! - Ted