From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DB2CC48BD7 for ; Wed, 26 Jun 2019 00:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3A9A2086D for ; Wed, 26 Jun 2019 00:23:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726374AbfFZAXM (ORCPT ); Tue, 25 Jun 2019 20:23:12 -0400 Received: from mx.ewheeler.net ([66.155.3.69]:47178 "EHLO mx.ewheeler.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725782AbfFZAXL (ORCPT ); Tue, 25 Jun 2019 20:23:11 -0400 Received: from localhost (localhost [127.0.0.1]) by mx.ewheeler.net (Postfix) with ESMTP id 439D3A0692; Wed, 26 Jun 2019 00:23:10 +0000 (UTC) X-Virus-Scanned: amavisd-new at ewheeler.net Received: from mx.ewheeler.net ([127.0.0.1]) by localhost (mx.ewheeler.net [127.0.0.1]) (amavisd-new, port 10024) with LMTP id XUUrvMZH-9KD; Wed, 26 Jun 2019 00:23:09 +0000 (UTC) Received: from mx.ewheeler.net (mx.ewheeler.net [66.155.3.69]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx.ewheeler.net (Postfix) with ESMTPSA id 769DFA067D; Wed, 26 Jun 2019 00:23:09 +0000 (UTC) Date: Wed, 26 Jun 2019 00:23:09 +0000 (UTC) From: Eric Wheeler X-X-Sender: lists@mx.ewheeler.net To: "Martin K. Petersen" cc: Coly Li , linux-block@vger.kernel.org, Jonathan Corbet , Kent Overstreet , "open list\\:DOCUMENTATION" , open list , "open list\\:BCACHE \\(BLOCK LAYER CACHE\\)" Subject: Re: [PATCH] bcache: make stripe_size configurable and persistent for hardware raid5/6 In-Reply-To: Message-ID: References: <1561245371-10235-1-git-send-email-bcache@lists.ewheeler.net> <200638b0-7cba-38b4-20c4-b325f3cfe862@suse.de> User-Agent: Alpine 2.11 (LRH 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 24 Jun 2019, Martin K. Petersen wrote: > > Perhaps they do not set stripe_width using io_opt? I did a grep to see > > if any of them did, but I didn't see them. How is stripe_width > > indicated by RAID controllers? > > The values are reported in the Block Limits VPD page for each SCSI block > device and are thus set by the SCSI disk driver. IOW, the RAID > controller device drivers have nothing to do with this. > > For RAID controllers specifically, the controller firmware will fill out > the VPD fields for each virtual SCSI disk when you configure a RAID > set. For pretty much everything else, the Block Limits come straight > from the device itself. > > Also note that these values aren't specific to RAID controllers at > all. Most new SCSI devices, including disk drives and SSDs, will fill > out the Block Limits VPD page one way or the other. Even some USB > storage devices are providing this page. Thanks, that makes sense. Interesting about USB. > > If they do set io_opt, then at least my Areca 1883 does not set io_opt > > as of 4.19.x. I also have a LSI MegaRAID 3108 which does not report > > io_opt as of 4.1.x, but that is an older kernel so maybe support has > > been added since then. > > I have several MegaRAIDs that all report it. But it depends on the > controller firmware. > > > Is it visible through sysfs or debugfs so I can check my hardware > > support without hacking debugging the kernel? > > To print the block device topology: > > # lsblk -t > > or look up io_opt in sysfs: > > # grep . /sys/block/sdX/queue/optimal_io_size > > You can also query a SCSI device's Block Limits directly: > > # sg_vpd -p bl /dev/sdX Perfect, thank you for that. I've tried the following controllers that I have access to. One worked (hspa/HP Gen8 Smart Array Controller), but the others I tried are not providing VPDs: * LSI 2108 (Supermicro) * LSI 3108 (Dell) * Areca 1882 * Areca 1883 * Fibrechannel 8gbe connected to a Storwize 3700 ~]# sg_vpd -p bl /dev/sdb VPD page=0xb0 fetching VPD page failed > If you want to tinker, you can simulate a SCSI disk with your choice of > io_opt: > > # modprobe scsi_debug opt_blks=N > > where N is the number of logical blocks to report as being the optimal > I/O size. Neat, thanks for the hint! -Eric > > -- > Martin K. Petersen Oracle Linux Engineering >