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 7EED32EFD95 for ; Mon, 19 Jan 2026 07:27:03 +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=1768807625; cv=none; b=t8Iur3WGfNuhBcc9awVXRXqNoYifQFpN3yUU/8U0UtA2z6ExPWwaErj1iOHBmqk9vVo5qZ9yP1ONjQuWQczXS+NyMPlFPhCA1zbmrXyZoY4uAKxxtDUqthb2z6CAapReqXa9m7AJfXBlKtC8Hu1iri+U+rRxhgAENOEk2vcSEV0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768807625; c=relaxed/simple; bh=QTEOuHoe9hve107xXTOJyTbyEOKlNELu8/RM5E7NtHc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cHldI/xv7vTXegekIRCYWK78vHHI0psxlhxOn+c8jmi9/PGrsNk1uh4de1xHNu/oJvIpo/fWX3AgYrdkMfnXCPOmgXCCC8F06m4gzEO52I/E01f4x+ZD4TpKQvJpGZeEZbM2HTzUpo20erqKzBFxg5R8kPySukp/2k8CmUDNZLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=trFiHa2i; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="trFiHa2i" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=AXkrrRp1oRr46Y2GHuTWr5vYga6vqugCE7xACuabfgk=; b=trFiHa2ib+mb/F6KYF6Pher42j btyuUopZzp8N1LgQccphpzBprkp1hRcl0SC8k/NXnkOKXsq6i5XcnsBGkHEdvYLQBvPH6lD+j+1CB mjIcVmoH6PjAQvIeigZ3D3emlafCZ2eXlnsqwy/khbxfwYmllhdNzST7Jh7GWFDJ7tKNmOFF4G/bL TO/XRU8s49XOvQa0M2INtI1t56wKM/RY/8P3pOngZNItkgodPMPvWZFHmP6BruNYjD3FTXgNwgnzP m/qxBLdqaZPj6xSGuq3T2d4qS6uF1efkZ41dB7btSn9FhBjmYdqPtf8INQVGbOnAo04PyKrXT7g+K KlNK7N6g==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vhjfD-00000001TWE-0Pw0; Mon, 19 Jan 2026 07:27:03 +0000 Date: Sun, 18 Jan 2026 23:27:03 -0800 From: Christoph Hellwig To: Yu Kuai Cc: Christoph Hellwig , linux-raid@vger.kernel.org, linan122@huawei.com, xni@redhat.com, dan.carpenter@linaro.org Subject: Re: [PATCH v5 07/12] md: support to align bio to limits Message-ID: References: <20260114171241.3043364-1-yukuai@fnnas.com> <20260114171241.3043364-8-yukuai@fnnas.com> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Jan 19, 2026 at 03:21:14PM +0800, Yu Kuai wrote: > Hi， > > 在 2026/1/19 14:47, Christoph Hellwig 写道: > > On Sun, Jan 18, 2026 at 07:40:23PM +0800, Yu Kuai wrote: > >> No, the chunk_sectors and io_opt are different, and align io to io_opt > >> is not a general idea, for now this is the only requirement in mdraid. > > The chunk size was added for (hardware) devices that require I/O split at > > a fixed granularity for performance reasons. Which seems to e exactly > > what you want here. > > > > This has nothing to do with max_sectors. > > For example, 32 disks raid5 array with chunksize=64k, currently the queue > limits are: > > chunk_sectors = 64k > io_min = 64k > io_opt = 64 * 31k > max_sectors = 1M > > It's correct to split I/O at 64k boundary to avoid performance issues, however > split at 64 *31k boundary is what we want to get best bandwidth. > > So, if we simply changes chunk_sectors to 64 * 31k, it will be incorrect, because > 64k boundary is still necessary for small IO. What do you mean with "necessary for small IO"?