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 43E8A1E515 for ; Wed, 8 Jan 2025 19:12:39 +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=1736363560; cv=none; b=uMbFt2dFXA09NHEkI/qNUl2xus7gQ15+buKSFp3xEs8hdOpkc9qb2VFhaWA7wbcGsD1M9/ohsuDmTcOj84oYNkVkF9bl/i78X9f9E0c4NAY78Cdm51ES4sZyhkmgC7oMInb7+VxomBwecZqILV+4NiuZICLpSXQe9NB6uTLWK64= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736363560; c=relaxed/simple; bh=49/FqZ2wJzPsEP2SrZYqtKJSXDQny/PrPSPleDh0Ufw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aQiZUUO33RN/iRKlqSPPRXmC7d6wsfotYbT47hpPazbto0yDWhzE5eZlYbb7hMoSqqA715npOkE9Yl1ASilz1BSy/Wai0T7rIPCZpl0hribDN1qFGMWYIcZP4qVADfUGdf5dILgSBHQwlRwBHqFgSGIq35ODvWbw0SEmtsoS+Lk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EbLzWvGu; 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="EbLzWvGu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83079C4CED3; Wed, 8 Jan 2025 19:12:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736363559; bh=49/FqZ2wJzPsEP2SrZYqtKJSXDQny/PrPSPleDh0Ufw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EbLzWvGurWhFMXZd/3TSAXxoiAklcDLp4Ush8UsoW6p7Ut36rIrCvSbt9rnGXSdcT U3mQzKzZ8rEjha5amjiHTjz3sIlour93tGad35T6N+ak9en8xSoxi9ItVvQZY8/G9v k1J2vxGj7GDByaa5HyXmq2kV7rvR4WykX7vUN8/vK/k8gTkQAYU84GXNJ7rCvGkLpY a+a1JxfA0mJ5rfy7+IxPQC+RFwCzuE/NpdOYSzMc1HHJyyPOGjTzBVOO3SjbeUvPP+ qSR9usTUh5rPdiXmEtGxxXwbR/pjNiR9MDecgrQiSPqbWMJfdRx+EQ5xVp5Y/CkMv9 Rw8bSLJIUW+xw== Date: Wed, 8 Jan 2025 11:12:38 -0800 From: Luis Chamberlain To: Keith Busch Cc: Bart Van Assche , 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> <386a5388-1b1b-4e5a-ad9c-0da1840f12ee@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: On Sat, Jan 04, 2025 at 04:59:39PM -0800, Keith Busch wrote: > On Fri, Jan 03, 2025 at 08:04:32PM -0800, Luis Chamberlain wrote: > > On Fri, Jan 03, 2025 at 06:15:55PM -0800, Bart Van Assche wrote: > > > On 1/3/25 5:47 PM, Luis Chamberlain wrote: > > > > 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, > > > Hmm ... aren't max_segment_size values that are larger than the page > > > size supported since day one of the Linux kernel? Or are you perhaps > > > referring to Ming's multi-page bvec patch series that was merged about > > > six years ago? > > > > Try aiming high for a single 2 MiB for a single IO on x86_64 on NVMe, that is > > currently not possible. At the max 128 NVMe number of DMA segments, and we have > > 4 KiB per DMA segment, for a 512 KiB IO limit. Should multi-page bvec > > enable to lift this? > > You need huge pages to guarantee you can reach those transfer sizes in a > single command. Otherwise you need to get lucky with larger contiguous > folios, which can certainly happen but it's just not as desterministic. Now with min-order support, it is deterministic. Luis