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 189E0309F13 for ; Mon, 27 Oct 2025 15:19:53 +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=1761578394; cv=none; b=s7A530pdoHM5Neobyv5I7VV5mLWj4blx53IqqHaKKf3rv1u5UIAFKD1b/YjfDq0Zh9TbbRVI7qxXEozIi3ZOI4nrE+dcQEetByW/Z7Q2P2NDwPXGc3a1LzVi6t9GL//emr0GCRfl0189S0SwfiV0XF2Ewn/UszCBKtnTkaQoDAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761578394; c=relaxed/simple; bh=LVbFEnXvaAEdnO6nPCdiGV/PQAdS5u8wgflWYdzpv78=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ay+ry++1csq0s8FkXQiaZn5fORj1F0rRr+SfPp8tBG2cG/gj5lftsAaI2jEBRyPHVq4jJTbAlXCuIlFWjRn4upCnUNqXWsYF4ujJGjn4XoV9ekBZk39ZQeg8lLrkDWv+n0yibnEuYvxbeeDE3IoSHAP2LklLmiltv2F4Bsp32sk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DWb3JMS9; 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="DWb3JMS9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 165EDC4CEF1; Mon, 27 Oct 2025 15:19:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761578393; bh=LVbFEnXvaAEdnO6nPCdiGV/PQAdS5u8wgflWYdzpv78=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DWb3JMS9Nq3HoT8t99B8lcCwWO1SIwv4Ad5EqohBhM+rlvCQLl6+MhyhU14lTRXqH zTSaZ4TifY8t2p2mAS+WbIkaHzP25CUd9KUDW7T4as/5gQfhErb7pyHR5VMcy9DJFp 6mHjoZBWbbeIZVbh+gpHBsb60st60qbwjKK6imTIeROkSTorXc4Qu7OYMWA9hh94sX ABsYAVRoLSKqoFu2wDtgjvZ874mPqilQ3ynHfArhdkiqsnBHsMzuvKIxZ1+qd4dJAC b2Cie7MnJTvT3bAZiA0aorNPcJRwgSEfBUcTwXzomVcZ+u/gdm7kALS1fb3bs6hTpL zZC+1h+9IY4jw== Date: Mon, 27 Oct 2025 11:19:52 -0400 From: Mike Snitzer To: Chuck Lever Cc: Christoph Hellwig , NeilBrown , Jeff Layton , Olga Kornievskaia , Dai Ngo , Tom Talpey , linux-nfs@vger.kernel.org, Chuck Lever Subject: Re: [PATCH v7 05/14] NFSD: @stable for direct writes is always NFS_FILE_SYNC Message-ID: References: <20251024144306.35652-1-cel@kernel.org> <20251024144306.35652-6-cel@kernel.org> <3c3774a9-a1f1-46a8-a81f-ebc3dde228c3@kernel.org> <7093445f-604a-4bfd-9104-b9f70138ed07@kernel.org> 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: <7093445f-604a-4bfd-9104-b9f70138ed07@kernel.org> On Mon, Oct 27, 2025 at 11:04:47AM -0400, Chuck Lever wrote: > On 10/27/25 10:58 AM, Mike Snitzer wrote: > >>> The current approach of using IOCB_DSYNC|IOCB_SYNC have performed > >>> really well on modern NVMe servers. > >> NVMe does not implement a concept called servers. > > But you're aware that servers have NVMe devices in them.. that's all I > > meant. All of these NFSD_IO_DIRECT changes have been developed and > > tested in modern servers with 8 NVMe, see: > > https://www.youtube.com/watch?v=tpPFDu9Nuuw > > > > (NOTE: results covered in this session did _not_ have the benefit > > of NFSD responding to client with NFS_FILE_SYNC to avoid COMMIT, the > > ability to do so was discussed at Bakeathon and was acted on with > > these latest NFSD Direct patchsets). > > This is why I suspect that leaving direct writes as UNSTABLE, rather > than promoting them to FILE_SYNC, is probably not going to make much > difference to Jonathan's benchmark results. That's just a guess though. > > IOW the memory costs of sticking with UNSTABLE + COMMIT have already > been demonstrated, and it's low. > > The v8 of this series will go back to that idea, and if you want, you > can benchmark it again. If it regresses, we can stick with FILE_SYNC. > It's just ones and zeroes, as they say. OK.