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 3EF4A29AB09; Thu, 12 Jun 2025 16:12:11 +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=1749744732; cv=none; b=OlL1CNqUKG1BSlugDMGYPR/crJOU1WyUbHqlNpAHje/s5dN2THaTqOxeOzxj2KHUTQeRmkop3A301KJIqBUfO8sYm8DnMrxl1HTu9cbrsmRPVOsOO3gZk86thBcN1qge4ehcOGDsfddbwSMFG1KhccHE7BaGsIVmfXXPnuGSFJE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749744732; c=relaxed/simple; bh=FSA3tiw9gewwK5LBaaWrec3fha2fNeVi5ofPGkDW/kA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iS9htWBFSvLgAItdmP2sPibKFaBe9h3HBfUdNccicw1ZtN/82peLmY7aLiq9ynHj+W9Nju/mGdMAAroAmt2WddWgIqIhUBD6qGL98qt4WFleraIZudPAvY9S3YFTCe0a4XIXv5A2USFR9H0Bg/UMieLnh3QqcyQgexC7ZRwrD3M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q3yRNl9J; 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="Q3yRNl9J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EDE7C4CEEA; Thu, 12 Jun 2025 16:12:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749744731; bh=FSA3tiw9gewwK5LBaaWrec3fha2fNeVi5ofPGkDW/kA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q3yRNl9J9xBoZR3cBB8aAm+uqPxAT7QvfIEQ0aITxswlh7EeUeb68K5hGizKd2M0m kdR0giDUjagSv/9NRlm2CaX/UrGtWLbWQFCPVvtY2Zp0oJ/PqRda4tMlBXHqSK3x1g n1dc7T8Y2wXUk/BepBX1y5nGZH3kudbQto9Ia4aMdyqkxKxRSl9pOD0YBMVQJIyl10 zmw3mLD8Y+D3ygRLHHnSQFCKYx0fn+UyMU1bn5plgAl8IBtGa4ZGC4JMG0m4BVfzmn cAtxAskzETYnv1/il1FWTHcj1GcxONMRni0MCQID+tj82r4ZmpItSa69kszuyM8rCZ Rx2QW6ISINVmw== Date: Thu, 12 Jun 2025 12:12:10 -0400 From: Mike Snitzer To: Chuck Lever Cc: Benjamin Coddington , Jeff Layton , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe Subject: Re: need SUNRPC TCP to receive into aligned pages [was: Re: [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO] Message-ID: References: <20250610205737.63343-2-snitzer@kernel.org> <4b858fb1-25f6-457f-8908-67339e20318e@oracle.com> <7c48e17c4b575375069a4bd965f346499e66ac3a.camel@kernel.org> <110c7644b829ce158680979e6cd358193ea3f52b.camel@kernel.org> <5D9EA89B-A65F-40A1-B78F-547A42734FC2@redhat.com> <04acd698-a065-4e87-b321-65881c2f036d@oracle.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: <04acd698-a065-4e87-b321-65881c2f036d@oracle.com> On Thu, Jun 12, 2025 at 11:58:27AM -0400, Chuck Lever wrote: > On 6/12/25 11:56 AM, Mike Snitzer wrote: > > On Thu, Jun 12, 2025 at 10:17:22AM -0400, Benjamin Coddington wrote: > >> > >> What's already been mentioned elsewhere, but not yet here: > >> > >> The transmitter could always just tell the receiver where the data is, we'd > >> need an NFS v3.1 and an extension for v4.2? > >> > >> Pot Stirred, > >> Ben > > > > Yeah, forgot to mention giving serious consideration to extending > > specs to make this happen easier. Pros and cons to doing so. > > > > Thanks for raising it. > > > > Mike > > NFS/RDMA does this already. Let's not re-invent the wheel. TCP is ubiquitous, I know you seem to really not want us to seriously pursue fixing/improving things to allow for the WRITE payload to be stored in an aligned buffer that allows zero-copy but... the value of not requiring any RDMA hardware or client changes is too compelling to ignore. RDMA either requires specialized hardware or software (soft-iwarp or soft-roce). Imposing those as requirements isn't going to be viable for a large portion of existing deployments.