From patchwork Thu May 28 08:42:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hannes Reinecke X-Patchwork-Id: 213866 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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 C6613C433DF for ; Thu, 28 May 2020 08:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F3FB2088E for ; Thu, 28 May 2020 08:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727876AbgE1Ixx (ORCPT ); Thu, 28 May 2020 04:53:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:49300 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727814AbgE1Ixx (ORCPT ); Thu, 28 May 2020 04:53:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id A7AC0B21F; Thu, 28 May 2020 08:53:50 +0000 (UTC) From: Hannes Reinecke To: "Martin K. Petersen" Cc: Christoph Hellwig , Doug Gilbert , Johannes Thumshirn , Daniel Wagner , James Bottomley , linux-scsi@vger.kernel.org, Hannes Reinecke Subject: [PATCHv2 0/4] Date: Thu, 28 May 2020 10:42:23 +0200 Message-Id: <20200528084227.122885-1-hare@suse.de> X-Mailer: git-send-email 2.16.4 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Hi all, based on the ideas from Doug Gilbert here's now my take on using xarrays for devices and targets. It revolves around two ideas: - The scsi target 'channel' and 'id' numbers are never ever used to the full 32 bit range; channels are well below 10, and no driver is using more than 16 bits for the id. So we can reduce the type of 'channel' and 'id' to 16 bits, and use the 32 bit value 'channel << 16 | id' as the index into the target xarray. - Most SCSI LUNs are below 256 (to ensure compability with older systems). So there we can use the LUN number as the index into the xarray; for larger LUN numbers we'll allocate a separate index. With these changes we can implement an efficient lookup mechanism, devolving into direct lookup for most cases. And iteration should be as efficient as the current, list-based, approach. This patchset now survives basic testing, hence I've removed the 'RFC' tag from the initial patchset. Changes to v1: - Fixup __scsi_iterate_devices() - Include reviews from Johannes - Minor fixes - Include comments from Doug Hannes Reinecke (4): scsi: convert target lookup to xarray target_core_pscsi: use __scsi_device_lookup() scsi: move target device list to xarray scsi: remove direct device lookup per host drivers/scsi/hosts.c | 3 +- drivers/scsi/scsi.c | 131 ++++++++++++++++++++++++++++--------- drivers/scsi/scsi_lib.c | 9 ++- drivers/scsi/scsi_scan.c | 66 ++++++++----------- drivers/scsi/scsi_sysfs.c | 42 ++++++++---- drivers/target/target_core_pscsi.c | 8 +-- include/scsi/scsi_device.h | 21 +++--- include/scsi/scsi_host.h | 5 +- 8 files changed, 179 insertions(+), 106 deletions(-)