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=-6.8 required=3.0 tests=BAYES_00, 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 7A0C7C433E9 for ; Wed, 6 Jan 2021 10:25:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 454932311B for ; Wed, 6 Jan 2021 10:25:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726422AbhAFKZR (ORCPT ); Wed, 6 Jan 2021 05:25:17 -0500 Received: from mx2.suse.de ([195.135.220.15]:54026 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726051AbhAFKZQ (ORCPT ); Wed, 6 Jan 2021 05:25:16 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 10DE7AD29; Wed, 6 Jan 2021 10:24:35 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id C3E3B1E0812; Wed, 6 Jan 2021 11:24:34 +0100 (CET) From: Jan Kara To: Jens Axboe Cc: , Ming Lei , Jan Kara Subject: [PATCH 0/2 v2] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues Date: Wed, 6 Jan 2021 11:24:26 +0100 Message-Id: <20210106102428.551-1-jack@suse.cz> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello! This patch series aims to fix a regression we've noticed on our test grid when support for multiple HW queues in megaraid_sas driver was added during the 5.10 cycle (103fbf8e4020 scsi: megaraid_sas: Added support for shared host tagset for cpuhotplug). The commit was reverted in the end for other reasons but I believe the fundamental problem still exists for any other similar setup. The problem manifests when the storage card supports multiple hardware queues however storage behind it is slow (single rotating disk in our case) and so using IO scheduler such as BFQ is desirable. See the second patch for details. Honza