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=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 75F12C433E1 for ; Wed, 27 May 2020 14:14:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51A7F207D8 for ; Wed, 27 May 2020 14:14:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387696AbgE0OOM (ORCPT ); Wed, 27 May 2020 10:14:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:51218 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730098AbgE0OOM (ORCPT ); Wed, 27 May 2020 10:14:12 -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 B31FEABBD; Wed, 27 May 2020 14:14:13 +0000 (UTC) From: Hannes Reinecke To: "Martin K. Petersen" Cc: Christoph Hellwig , Doug Gilbert , Daniel Wagner , James Bottomley , linux-scsi@vger.kernel.org, Hannes Reinecke Subject: [RFC PATCH 0/4] scsi: use xarray for devices and targets Date: Wed, 27 May 2020 16:13:56 +0200 Message-Id: <20200527141400.58087-1-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: - 'channel' and 'id' 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 change 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 is compile-tested only, to give you an impression of the overall idea and to get the discussion rolling. 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 | 129 ++++++++++++++++++++++++++++--------- drivers/scsi/scsi_lib.c | 8 +-- drivers/scsi/scsi_scan.c | 66 +++++++++---------- drivers/scsi/scsi_sysfs.c | 39 +++++++---- drivers/target/target_core_pscsi.c | 8 +-- include/scsi/scsi_device.h | 21 +++--- include/scsi/scsi_host.h | 5 +- 8 files changed, 175 insertions(+), 104 deletions(-) -- 2.16.4