From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 008.lax.mailroute.net (008.lax.mailroute.net [199.89.1.11]) (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 3E1831BD9C2 for ; Fri, 3 Jan 2025 22:12:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735942370; cv=none; b=sdnxkir77wUMvZVDHVZ3ydie48upPxFTWsgVEFEpo4aL+VjZGc6BGctj6bV7jFs/Pra4lwQb+TITieB1I0dCu+Ksmkmnu2+OVk85pBBT72Xw8f7YQYu+9xz+T3UQPi0iuc0ZZ1P3fWRKRFLiv4Pnq1F9Hh99OCpVMpFyXIoI0ws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735942370; c=relaxed/simple; bh=Hhx6nnjmWQQ5H9KEPn0rSMjUwALg95RecFhahughkO4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Owzz7y3Cb3oGG7AfXKTZuVYv3o6go5n4Mnukod2mv3Bzl+2Qnf1+V90ADpsvr+45bUP9HNc22N3+M28+Ad2Y1N2xdgiM60Q7atW55yGzp0RhWRrZqjxGUyedcTyyZ+qERE1bdVd/RRHsaNSVLeSAg6+6pXcqOUN/Z+UaGk57GNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=Ex36IbkI; arc=none smtp.client-ip=199.89.1.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="Ex36IbkI" Received: from localhost (localhost [127.0.0.1]) by 008.lax.mailroute.net (Postfix) with ESMTP id 4YPyVy38grz6ClbJ9; Fri, 3 Jan 2025 22:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1735942359; x=1738534360; bh=Hhx6nnjmWQQ5H9KEPn0rSMjU wALg95RecFhahughkO4=; b=Ex36IbkIiLduhzw9mKP/LkPM+1IjQQfELyDe/CRb txS5W8gsGvSYacp8fCHOohtsvLDg1r62f5/V6LzECw6Gda0IpRIcAwA9rGDeNcNk mEklOhoxYLfVv5jVORBK85SRWqvnB3llErEhr4MZpuznCIet/mRu/XOX1St/mnz4 oU+Mp83PPDUZ+ig8LkNhDTcuqz13/LzOXmcNHs+QFya5qyg4F4b/c577+o+neBZj K6KQW58RZ5I+t/LnhP3hrc1bETava3iErZCArJjYEFQ8jfdIQYZG5IyvkseCK3Uo Ndljx02SHZ2NCP6jUenf34UeTmc2ruT/F4f0iZS3gEFGLQ== X-Virus-Scanned: by MailRoute Received: from 008.lax.mailroute.net ([127.0.0.1]) by localhost (008.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id G430Tf08iSU1; Fri, 3 Jan 2025 22:12:39 +0000 (UTC) Received: from [192.168.3.219] (c-73-231-117-72.hsd1.ca.comcast.net [73.231.117.72]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 008.lax.mailroute.net (Postfix) with ESMTPSA id 4YPyVs21Tqz6ClY9Q; Fri, 3 Jan 2025 22:12:36 +0000 (UTC) Message-ID: <1b1bf316-359a-4bec-8195-0152cd706001@acm.org> Date: Fri, 3 Jan 2025 14:12:36 -0800 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] block: make queue limits workable in case of 64K PAGE_SIZE To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Yi Zhang , Luis Chamberlain , John Garry , Christoph Hellwig References: <20250102015620.500754-1-ming.lei@redhat.com> <0b423229-f928-4210-9351-dca353071231@acm.org> <0b34bfc9-2cd3-40a8-8153-3207a6d62f8c@acm.org> Content-Language: en-US From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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. > From the link, you have storage controllers with DMA segment size which > is less than 4K, which may never get supported by linux kernel. As mentioned in the cover letter of that patch series, I came up with that patch series to support a DMA controller with max_segment_size of 4 KiB on a system with a PAGE_SIZE of 16 KiB. Thanks, Bart.