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 C11E732254D for ; Wed, 27 Aug 2025 08:06:31 +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=1756281991; cv=none; b=iLyBdOATAUdlfYTw5t94XEg9lewBaKMhm3M3ziDGaqnpUs/p2khcZyvdN0DqM/szpSSzCBpnLS+i1U7w7UmefdSDQGnCR1lC/nZcCuOL73THJLvFLy7648iofIW+VgPP3kIndmlzk9LTGKZRqlZqy3IhLBPJkOj1qhn0/uuqRw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756281991; c=relaxed/simple; bh=zGQUkk728L+OVMQRWnn6I3XGCVDq5RhtFvWlJYrkX7o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VbvOPcTqfUAQwloEfrw9lgPXlGf75PjKIJiRd0B99rCEDMk1NMuAZNE1e9b4kIEWL5WzHmy/eIwFSZIzkMf0PcR8NMY8CBXZ6FYNyBSaL7xfuC1YqxCUJ8LjH9KZqYEZK8ihb+Qcy41ptu5G+SAUDHkQXo6noTua1Y7v6M+KvfU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ma+a2TfN; 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="Ma+a2TfN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4EBFC4CEEB; Wed, 27 Aug 2025 08:06:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756281991; bh=zGQUkk728L+OVMQRWnn6I3XGCVDq5RhtFvWlJYrkX7o=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Ma+a2TfNrMjTfWt80uvDdVDuAiLZMs1s3BHLxiXLQenARcYi7bW1yewJxuEz2VJR4 lL/CV4okv1aZoxp/T5OGZNZSg6+YX5at7u4jkuk7JZmFKfhm9p5wRKqae9rJ+Jhmjq jRnQ30DiLtCmxdXzVUZcoFJawJwh+LjssKllr22gN+erMp8IfcglDGcaZsJKwJwDcg UNc5TMHA0V0VycMmgj3FMSMIOfJMsA/IinQqvJNXID5zH1IrYppNwRK32nYwGTvJgy F4lUt7U3JNoDJRxscwHZQ2KEWJdFgE6D4P/pfZPzO4BYIlY7wt9R6CO2Id9GA//7VE AnjWfPXmnmWWw== Message-ID: Date: Wed, 27 Aug 2025 17:03:39 +0900 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 v2] block: Increase BLK_DEF_MAX_SECTORS_CAP To: Christoph Hellwig , Sebastian Andrzej Siewior Cc: Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" References: <20250618060045.37593-1-dlemoal@kernel.org> <175078375641.82625.9467584315092336312.b4-ty@kernel.dk> <20250827070705.4iWhHGPE@linutronix.de> <20250827073836.GA25169@lst.de> <20250827075221.6hTi-i7m@linutronix.de> <20250827080003.GA26652@lst.de> From: Damien Le Moal Content-Language: en-US Organization: Western Digital Research In-Reply-To: <20250827080003.GA26652@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/27/25 5:00 PM, Christoph Hellwig wrote: > On Wed, Aug 27, 2025 at 09:52:21AM +0200, Sebastian Andrzej Siewior wrote: >>> this for you, you could also reproduce it before by say doing a large >>> direct I/O read. >> >> On a kernel without that commit in question? Booting Debian's current >> v6.12 and >> | dd if=vmlinux.o of=/dev/null bs=1G count=1 iflag=direct >> >> works like a charm. According to strace it does >> | openat(AT_FDCWD, "vmlinux.o", O_RDONLY|O_DIRECT) = 3 >> | dup2(3, 0) = 0 >> | lseek(0, 0, SEEK_CUR) = 0 >> | read(0, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\1\0>\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 1073741824) = 841980992 >> >> so it should be what you asked for. Asked for 1G, got ~800M. > > This is probably splitting thing up into multiple bios because your > output memory is fragmented. You'd have to do it into hugetlbfs or > vma otherwise backed by very larger folios. and also need: echo 4096 > /sys/block/sdX/queue/max_sectors_kb or some large number. But given that commit 345c5091ffec sets the default to 4MiB, I/Os are split to 4M and trigger the issue. So there is likely a cut-off command size < 4M where things stop working with this adapter. -- Damien Le Moal Western Digital Research