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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A6D71C4320A for ; Fri, 27 Aug 2021 14:09:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88B2C60F42 for ; Fri, 27 Aug 2021 14:09:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236500AbhH0OKj (ORCPT ); Fri, 27 Aug 2021 10:10:39 -0400 Received: from vps.thesusis.net ([34.202.238.73]:35896 "EHLO vps.thesusis.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231571AbhH0OKj (ORCPT ); Fri, 27 Aug 2021 10:10:39 -0400 X-Greylist: delayed 452 seconds by postgrey-1.27 at vger.kernel.org; Fri, 27 Aug 2021 10:10:38 EDT Received: by vps.thesusis.net (Postfix, from userid 1000) id DEF3E47FAC; Fri, 27 Aug 2021 10:01:47 -0400 (EDT) References: <20210827075045.642269-1-damien.lemoal@wdc.com> User-agent: mu4e 1.5.13; emacs 27.1 From: Phillip Susi To: Damien Le Moal Cc: Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" , linux-scsi@vger.kernel.org Subject: Re: [PATCH v6 0/5] Initial support for multi-actuator HDDs Date: Fri, 27 Aug 2021 09:58:38 -0400 In-reply-to: <20210827075045.642269-1-damien.lemoal@wdc.com> Message-ID: <874kbbugtw.fsf@vps.thesusis.net> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Damien Le Moal writes: > Single LUN multi-actuator hard-disks are cappable to seek and execute > multiple commands in parallel. This capability is exposed to the host > using the Concurrent Positioning Ranges VPD page (SCSI) and Log (ATA). > Each positioning range describes the contiguous set of LBAs that an > actuator serves. Are these ranges exlusive to each actuator or can they overlap? > This series does not attempt in any way to optimize accesses to > multi-actuator devices (e.g. block IO schedulers or filesystems). This > initial support only exposes the independent access ranges information > to user space through sysfs. Is the plan to eventually change the IO scheduler to maintain two different queues, one for each actuator, and send down commands for two different IO streams that the elevator attempts to keep sequential?