From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8906052D2CA for ; Wed, 9 Sep 2026 10:47:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950846; cv=none; b=gNVqL6xf57LxTMDiaBVzfcsWIfYpHmEAvP295mjv+XBR7HFigfSPwp59lquoeHP823mx9a+q/Hz+HxeplYiNdedRP6GXouv2uJtCFtT/fNZt16ZrYwUgNpqPrzeubxjmp7xv/pdbchLOzMvAjnfwzYYDhqkOxQ+Ge0kbxdlx37o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950846; c=relaxed/simple; bh=bpcndwsBPhC+HB7j7LgHgTKc4Et1K6S5MfF8xes9Vl0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=NDHO0bCc28+Hjb4eo0yge54pPe3N+6+DA6vZ+jFvo3T7rmprx4APus7xfv4EnYptgMyLw0vkJGtlMA/5sR7pnH74643zF3tDHlDKgZDi0Gc7xTohDGA8Euqj71PP3ggCZTY7oe+90Jy/d14l5ViG6SSMuRqf42o3hvYs1xsahJU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aVnvphq6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aVnvphq6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8B7C1F00A3D; Wed, 9 Sep 2026 10:47:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788950844; bh=bpcndwsBPhC+HB7j7LgHgTKc4Et1K6S5MfF8xes9Vl0=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=aVnvphq6Zr8s7K39pfy8dvuLzQ8h5cWOoRTbPTiJNOo5FBQvZsbebxP7mq5dOQqgF FJFsAAZ6RK0muAmhEt04qDuLjEx12V/2zOpL1lZ/jQQYzTHe/xz3/INcxmcpO/p6i+ GbOd/a+bHMfVSHGcEIVHeZ6oNyqiZNDIWbK20hWtDo73D2b83/pa5WKSViqj8JbfQo 1Ck41yYNT4E7xIpMWr6ucLMAJgy+g4rnteG39w2RGQJ6eCrrH5gN6+fQCwyK5Z72ar +Va4ScEIWY1bARoXoBvU/G4RPtBp7EUa8ykxjcJrMuOjGZGGA5VhzESXKQea/Vf0F8 1edhvG83YdUiw== Message-ID: <781c00257ef315000faf75a586b97ec2578629d1.camel@kernel.org> Subject: Re: NFS strategy for large number of file opens From: Jeff Layton To: Shyam Prasad N Cc: linux-nfs@vger.kernel.org, Trond Myklebust , Anna Schumaker Date: Wed, 09 Sep 2026 06:47:22 -0400 In-Reply-To: References: Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn 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thread to understand how NFS deals (or plans > > > to deal with) workloads that serially do open/close calls to a large > > > number of files in a directory? Think about a use case of tar of Linu= x > > > kernel source code on NFS shares. > > >=20 > > > AFAIK, local filesystems fare well for this workload compared to > > > network filesystems, as file opens are local, and file state is > > > maintained locally. For network filesystems, each open needs to go > > > over the wire to the server. > > >=20 > > > Has there been any proposals to improve perf for such workloads? > > > Could there be possible extensions to directory delegations, that > > > could allow the client to make opens async and batch them together to > > > the server in the background? IMO, the challenge is that such open > > > calls can fail. But can the clients be enabled to do many of these > > > failure checks (for example, the client could be allocated quota for > > > how many files it can create, be allowed to cache file permissions by > > > delegating them etc.)? > > >=20 > > > Looking forward to the responses. Thanks in advance. > >=20 > > You should resend this and cc linux-nfs@vger.kernel.org. >=20 > Hi Jeff, >=20 > linux-cifs mailing list is already in the cc. :) >=20 My mistake! > >=20 > > The big problem for untar workloads is that they are serialized at the > > VFS layer on the client. Neil Brown has been working on changing that. >=20 > Has this been discussed in the mailing list? Could you point me to > that discussion? >=20 >=20 He has some preparatory patches here: https://lore.kernel.org/linux-fsdevel/20260904215142.1060510-1-neilb@ownmai= l.net/ ...but that might not help with untar workloads after all. What Neil's set would enable is parallel creates in the same directory, but untar is usually single-threaded and so you might be stuck waiting on round trip delays anyway. If you're interested in speeding up untar-style workloads, you might want to check out the async create code we added to the Ceph client several years ago. Basically, the Ceph MDS issues a swath of inode numbers to the client when it has appropriate caps on the directory, and it can then do creates locally and trickle them back out to the MDS over time. Here are some slides from a few years ago: https://www.usenix.org/sites/default/files/conference/protected-files/vault= 20_slides_layton.pdf Cheers, --=20 Jeff Layton