From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 694F62DB791 for ; Thu, 8 Jan 2026 15:35:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767886554; cv=none; b=dtJKdkgb1vmuoDy+Us+NyXWecDghptkUy7VYPnvU1Xnd80NTf3ngR+E9cAKB/7HaSUK4e+asG3yKpks54jfgFcOJxjtoCQwehMyXR9sX0z5p+H9bIK7M/DiOYENKKK0E34erMHqD3bkk+oyBfuD6PWGxuvB5hogY9TtVvQiO8gM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767886554; c=relaxed/simple; bh=hW+Vui6mROgnB2D8+UB1HP7nqJ5ZaH0GN9WoITM/W3g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J08uS3H1h8ka87ZMKjUivk5ZNO2zyIEYG+XJ2idAVhi8WF4xmVA9KqRPjb5ohqdzTX8Nu912VtOaMX0Afa9RH+vw1UbHid8yjP4i50XBIA4mVBulT/C+vxwYYY7aqVLocz3v3/0C69T3AHbkSlDN3xAlifBNuZ8bkprC54XM4lc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 3716B67373; Thu, 8 Jan 2026 16:35:46 +0100 (CET) Date: Thu, 8 Jan 2026 16:35:46 +0100 From: Christoph Hellwig To: Chuck Lever Cc: Sagi Grimberg , Christoph Hellwig , Trond Myklebust , Anna Schumaker , linux-nfs@vger.kernel.org Subject: Re: add a LRU for delegations Message-ID: <20260108153546.GA7623@lst.de> References: <20260107072720.1744129-1-hch@lst.de> <0b0b21c1-0bfd-4e2e-9deb-f368a66f5e9c@app.fastmail.com> <20260107162202.GA23066@lst.de> <45ba87f3-2322-424b-95b1-9129a2537545@app.fastmail.com> Precedence: bulk X-Mailing-List: linux-nfs@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: <45ba87f3-2322-424b-95b1-9129a2537545@app.fastmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) On Thu, Jan 08, 2026 at 09:34:28AM -0500, Chuck Lever wrote: > The server and client have orthogonal interests here, IMO. > > The server is concerned with resource utilization -- memory consumed, > slots in tables, and so on -- that other active clients might benefit > from having freed. The server doesn't really care which delegations > are returned. > > A client wants to keep delegation state that applications are using, > and it knows best which ones those are. It can identify specific > delegations that are not being actively used and return those. Yes. A good way to deal with that is implementing RECALLY_ANY as I mentioned, which with these changes could reclaim off the end of the LRU. But as this series is a big change already, and doing fine grained recalls is another huge one I'd rather wait a bit before going there.