From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 3B762142E73; Thu, 12 Jun 2025 07:13:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749712415; cv=none; b=bUJZZMyQLnr8sgUl9V9Zyoz79BhWHDLUs+LvLdg3+uETfe9wHU8s1Ee0rJ6Q6VBX1pL0b48C4cScIK8ONYJpCGphcZOvpjhCehfKVy4X9rqBVSS//Sv+W5mv9vAvF1ZxgpGtKCZt5cLKn41sQymUXlj1YhALSpjmMVh8vRtKzGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749712415; c=relaxed/simple; bh=KX7yFObNkQPwiJAvc4v9t3yn0dEmJ9qdNCzHnpoN24s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oUfCC7344zomNPTOFVgoHnhAh9iJwE6RzpLnTfbH93DnpjsJTvcOt89YwIZSzo7+Gp9yRLEARwNN845SGUzsEsIBTB9523SaQt3CVBxBg93ArBanAtzBZuSfk9OkLu4s2Fp2CxxnGs5KxOjs4wRx4U3qvksVIAn5VlQKt6HxjAY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=qE27VbKm; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qE27VbKm" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=2oEFjCSShK9uvDvw6XrUrclAWMENjlRPEowfuyu7U48=; b=qE27VbKmVa9lsjpdmAiQveZVGj Gm5UOrFQq9HDpk5R87vhNwMOeYNQgoHCLrpydHyxzP4Og/BY8qb3fyJNguBJMRPmDOQ+nSZV4ZsaC pLumFK/RA1xbz+h5W5bNpqSjU3kWmkBm9WRZnNgwJHJKP+nXv89JRuekcwYng+wI16Ef1cKahwytY 4KpG2sf6kR9ALNaHw2EyzVpyK364Wx3/r4U/CbZDfSWkl/HSHZTHayJQopmdWU1fPg+Z4+WVhb1NS npfAVNQtwfYCyKASGA9nGTqIKb3boAUBk5g5Wpifz/TgVaAWSHwTD65lYFEkhF1ZGWdXciL6Bdapt qDnX9TXA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPc7x-0000000CPJp-3VYr; Thu, 12 Jun 2025 07:13:33 +0000 Date: Thu, 12 Jun 2025 00:13:33 -0700 From: Christoph Hellwig To: Jeff Layton Cc: Mike Snitzer , Chuck Lever , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO Message-ID: References: <20250610205737.63343-1-snitzer@kernel.org> <20250610205737.63343-2-snitzer@kernel.org> <4b858fb1-25f6-457f-8908-67339e20318e@oracle.com> <7c48e17c4b575375069a4bd965f346499e66ac3a.camel@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <7c48e17c4b575375069a4bd965f346499e66ac3a.camel@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, Jun 11, 2025 at 04:29:58PM -0400, Jeff Layton wrote: > I think if we can crack the problem of receiving WRITE payloads into an > already-aligned buffer, then that becomes much more feasible. I think > that's a solveable problem. It's called RDMA :) To place write payloads into page aligned buffer, the NIC needs to split the various headers from the payload. The data placement part of RDMA naturally takes care of that. If you want to do it without TCP, you need hardware that is aware of the protocol headers up to the XDR level. I know and the days where NFS was a big thing there were NICs that could do this offload with the right firmware, and I wouldn't be surprised if that's still the case.