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 8CF4E20297C; Tue, 17 Jun 2025 04:37:02 +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=1750135025; cv=none; b=sw+d30zAo6hfsK0vpF2vhBWbMG3VGM+qqc0a+MVQg30i5C9A4NGFqEDo8f3uqgr+YXjEP584FOvMQiZJ74lVWz+laCdjijJz/nnAHZeox14sH7b8hAd5oZ9XVgvYMX7npzH3NHIh5EuDFEyAUa8b/QmYYIhS6Udf3G5bfwRuxfc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750135025; c=relaxed/simple; bh=4Ap0FTrxAFUSBUQw14fr+2BkK/PM+PVKpjjbqIrGnz0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CAjK74qHwvjzSVx2ALJxYkHXGNMIYIj5ZyGo4YRu2aEA+yliBYHcTlyn3cpDgIf/C/m65F1bun693z3wkAYjwscVUnPgt+BsSOJA895GXQ1GoW75CIinJtBwxASPtAZQud3H+Uw+Ppt224EwhvJM2sI7aJJIDrfoczHC2wT5Ma4= 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=qmY0Jt8Y; 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="qmY0Jt8Y" 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=7i0c1GgBy5rS73Gz5YEPluflZTgX6Cm9Oozv7odL4Ow=; b=qmY0Jt8YKSbArZsVuF4IAnEHD1 iac9zd03ob11Sjg/YPQn3Ue/AodgaLGz9YKoUmiXf9KLcWg3rqQLP/EQVv56ry8TWfZC1qTnkFG8N O3ED+rHo51tqEB60feC1UlYBirOuuUy91B6MmlxLzSzsjot94p5KnVXq4vifBUzz0cAIqRRwdMVTl OTQ8u2cQ/yzdMLRD8JqZqGM2kNK9C0t98mc4yeiYg5Boh28x1v0cLH3RgxFUN3CLBQgWxZBTNbDsP nbz6bcjKxz4+yex3xAudL92PZix2mWc2Cyzc3sI+RMRVx0oPpUtHhoNKve2kw+H9dmvFidYNeBsYr fPm5SZtA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uRO4D-00000006Avl-3KRY; Tue, 17 Jun 2025 04:37:01 +0000 Date: Mon, 16 Jun 2025 21:37:01 -0700 From: Christoph Hellwig To: Mike Snitzer Cc: Christoph Hellwig , Jeff Layton , Chuck Lever , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe , david.flynn@hammerspace.com 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: <7c48e17c4b575375069a4bd965f346499e66ac3a.camel@kernel.org> <110c7644b829ce158680979e6cd358193ea3f52b.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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Jun 16, 2025 at 12:07:42PM -0400, Mike Snitzer wrote: > But that's OK... my test bdev is a bad example (archaic VMware vSphere > provided SCSI device): it doesn't reflect expected modern hardware. > > But I just slapped together a test pmem blockdevice (memory backed, > using memmap=6G!18G) and it too has dma_alignment=511 That's the block layer default when not overriden by the driver, I guess pmem folks didn't are enough. I suspect it should not have any alignment requirements at all. > I'd like NFSD to be able to know if its bvec is dma-aligned, before > issuing DIO writes to underlying XFS. AFAIK I can do that simply by > checking the STATX_DIOALIGN provided dio_mem_align... Exactly.