From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 733F21B81CA for ; Sat, 13 Dec 2025 19:35:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765654511; cv=none; b=mIwgW32PUd4JNMf3Nik3WrMXZZtTu7whHY5Iegm1n1nCK9zsWXynxyjqWUea6WsmUhCHH1tNP+Iehm5Pj0+gE+z6uSlc1iLFEcr6VNYiyQx75JvTRZmeGgIeqyI3akKaFUpjtNbAANWC9L7f082WK8gNhpHyAM8EaSQHidb27/w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765654511; c=relaxed/simple; bh=lhIDqPX11pIVAellqCXy+w2jvKUBCsEzvQK8uswX/Nc=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=j0o+Dg8ZdHBj+a7IhRUYWWOKdJuP+CQuBP8qYrxoCWWjKspqG2ScWqV5bd7zUXGZDggBHLjNKR5hOdG9mxiuiHiKnQUVK/9sIj6Eb2XaPKAnPb/846daV+aI+i3k0zxC5GXZBx9hBhslIavd2d9zV5jtrL1BGAqNzLmjF5wcNhA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bia2WAhi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bia2WAhi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B787CC16AAE; Sat, 13 Dec 2025 19:35:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765654510; bh=lhIDqPX11pIVAellqCXy+w2jvKUBCsEzvQK8uswX/Nc=; h=Date:From:To:Cc:In-Reply-To:References:Subject:From; b=bia2WAhi8EZ+BbOQ8oJtgD4Hak6x8m5g859eLe5nW+xNiZPRdGli84UIJBqOCdEQp JLdAi8nZxbrF3MTQjf3FUWLCFAOkKeGoJUnUmkRvWjbH0QcR9jAijwPC1dxctM4+Nw g6kiE6B4+58BYyr+RRSXEDRRKfybZnKQAYNIXVhSKvv83bMcoue3Ed5PvZHM3/7PX5 yKUJCk9cE+Z1TZrJHy48KLpGIECBkrThTmgW+rQg731QHNKXAmGU3SnOq4iDoXTr4W NNdodNsngw62VRaMm39bAayXd8IkYZcmCTLOKGyWK4B+RP22iF+9PURZUqsBroPFle Xsi3i6Y1fttiA== Received: from phl-compute-10.internal (phl-compute-10.internal [10.202.2.50]) by mailfauth.phl.internal (Postfix) with ESMTP id DC604F4006C; Sat, 13 Dec 2025 14:35:09 -0500 (EST) Received: from phl-imap-15 ([10.202.2.104]) by phl-compute-10.internal (MEProxy); Sat, 13 Dec 2025 14:35:09 -0500 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdefudelvdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpuffrtefokffrpgfnqfghnecuuegr ihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjug hrpefoggffhffvvefkjghfufgtgfesthejredtredttdenucfhrhhomhepfdevhhhutghk ucfnvghvvghrfdcuoegtvghlsehkvghrnhgvlhdrohhrgheqnecuggftrfgrthhtvghrnh ephfffkefffedtgfehieevkeduuefhvdejvdefvdeuuddvgeelkeegtefgudfhfeelnecu vehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheptghhuhgtkh hlvghvvghrodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduieefgeelleel heelqdefvdelkeeggedvfedqtggvlheppehkvghrnhgvlhdrohhrghesfhgrshhtmhgrih hlrdgtohhmpdhnsggprhgtphhtthhopedutddpmhhouggvpehsmhhtphhouhhtpdhrtghp thhtohepnhgvihhlsegsrhhofihnrdhnrghmvgdprhgtphhtthhopegrnhhnrgeskhgvrh hnvghlrdhorhhgpdhrtghpthhtohepjhhlrgihthhonheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepthhrohhnughmhieskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepuggrih drnhhgohesohhrrggtlhgvrdgtohhmpdhrtghpthhtoheptghhuhgtkhdrlhgvvhgvrhes ohhrrggtlhgvrdgtohhmpdhrtghpthhtohepohhkohhrnhhivghvsehrvgguhhgrthdrtg homhdprhgtphhtthhopehtohhmsehtrghlphgvhidrtghomhdprhgtphhtthhopehlihhn uhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrgh X-ME-Proxy: Feedback-ID: ifa6e4810:Fastmail Received: by mailuser.phl.internal (Postfix, from userid 501) id B9E89780054; Sat, 13 Dec 2025 14:35:09 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AwGBrbvZiv0o Date: Sat, 13 Dec 2025 14:34:48 -0500 From: "Chuck Lever" To: "Jeff Layton" , "Chuck Lever" , NeilBrown , "Olga Kornievskaia" , "Dai Ngo" , "Tom Talpey" , "Trond Myklebust" , "Anna Schumaker" Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: <53080a86-df29-4321-8b51-c5af565cc6f2@app.fastmail.com> In-Reply-To: <20251213-nfsd-dynathread-v1-0-de755e59cbc4@kernel.org> References: <20251213-nfsd-dynathread-v1-0-de755e59cbc4@kernel.org> Subject: Re: [PATCH RFC 0/6] nfsd: allow for a dynamically-sized threadpool Content-Type: text/plain Content-Transfer-Encoding: 7bit On Fri, Dec 12, 2025, at 5:39 PM, Jeff Layton wrote: > This patchset changes nfsd to dynamically size its threadpool as > needed. The main user-visible change is the addition of new controls > that allow the admin to set a minimum number of threads. > > When the minimum is set to a non-zero value, the traditional "threads" > setting is interpreted as a maximum number of threads instead of a > static count. The server will start the minimum number of threads, and > then ramp up the thread count as needed. When the server is idle, it > will gradually ramp down the thread count. > > This control scheme should allow us to sanely switch between kernels > that do and do not support dynamic threading. In the case where dynamic > threading is not supported, the user will just get the static maximum > number of threads. An important consideration! > The series is based on a set of draft patches by Neil. There are a > number of changes from his work: > > 1/ his original series was based around a new setting that defined a > maximum number of threads. This one instead adds a control to define a > minimum number of threads. My concern is whether one or more clients can force this mechanism to continue creating threads until resource exhaustion causes a denial of service. I'm not convinced that setting a minimum number of threads is all that interesting. Can you elaborate on why you chose that design? -- Chuck Lever