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 C6A72EC5 for ; Sat, 4 Jan 2025 01:47:03 +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=1735955223; cv=none; b=fnIZnBGuh0+jVXIDqSyLyC6BlKa081Di9QAnFT41wuN51VzynP4JOLjWoL9vdp5AJ4me9UprMQWjD/J4CFVQAM1/Mn4upeRN8fiEVSpTsF5eKFFgjWJOmnBCphnnozTYaBaSwLCmnbWilcaNwb3i4YSpeSd7MywflzopDn8D67Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735955223; c=relaxed/simple; bh=iS3GsS+Bvag0lDhoiuduXF1ScdC0uYQGuTdJJzhAMPw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ldF1800HjTsSg47tnvs4rg9vG0Sjt2D9LAcj1CAhmJCbpk1TvVvF0pKMcQ7ySCvZ0Zih3V5IPWEwxZ/pAGc3PH9Ub5kJWGqoFGwekZa9M+5XF2B9czp+OQsskNDxfHMKXWFipsJMDJI6oVBPzcXNgAu2LEGYdCGr40mP6zQZyzg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ldwf7niU; 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="ldwf7niU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04254C4CED6; Sat, 4 Jan 2025 01:47:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735955223; bh=iS3GsS+Bvag0lDhoiuduXF1ScdC0uYQGuTdJJzhAMPw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ldwf7niU/ZgZaJB6+GY0R/UTfx204sTZiGOsSN7RWrzjeZpDUmHlFSIed4PbY4pvp XfsqY4E8XAGHPsSKEFxDtBlrZNDn/m/QuNlsY4wOyADSXfWG3k4ak2zfLS+i3La5ar stkwsRQBdi8sAqDukoSyHE6QfXI0kAfjZgGkLMtrN/URkb3r66xZV1DP0Wt8fGciru TOB4t/21dtIGgp48l83hQOhkdYW/p6o62h7TiMOgVmeIFygwZCfpyKeXjPJ+3ALlCa 1c1a2QvUnaWbpF7SRLExpbdAbTp5br3XqFiJFLBINBI8Zs+qqi20yp6CbQ5J4wM14F 22v1myzqZxlzA== Date: Fri, 3 Jan 2025 17:47:01 -0800 From: Luis Chamberlain To: Bart Van Assche Cc: Ming Lei , Jens Axboe , linux-block@vger.kernel.org, Yi Zhang , John Garry , Christoph Hellwig Subject: Re: [PATCH] block: make queue limits workable in case of 64K PAGE_SIZE Message-ID: References: <20250102015620.500754-1-ming.lei@redhat.com> <0b423229-f928-4210-9351-dca353071231@acm.org> <0b34bfc9-2cd3-40a8-8153-3207a6d62f8c@acm.org> <1b1bf316-359a-4bec-8195-0152cd706001@acm.org> Precedence: bulk X-Mailing-List: linux-block@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: <1b1bf316-359a-4bec-8195-0152cd706001@acm.org> On Fri, Jan 03, 2025 at 02:12:36PM -0800, Bart Van Assche wrote: > On 1/2/25 6:01 PM, Ming Lei wrote: > > But why does DMA segment size have to be >= PAGE_SIZE(4KB, 64KB)? > > From the description of patch 5/8 of my patch series: "If the segment > size is smaller than the page size there may be multiple segments per > bvec even if a bvec only contains a single page." The current block > layer implementation is based on the assumption that a single page > fits in a single DMA segment. Please take a look at patch 5/8 of my > patch series. While that addresses a smaller segment then page size this still leaves open the question of if a dma segment can be larger than page size, given our adoption of folios I don't see why we would constrain ourselves to a page size. I already have PoC code which enables this. Luis