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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 80622C433E0 for ; Sun, 9 Aug 2020 02:40:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57754206E2 for ; Sun, 9 Aug 2020 02:40:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SYWNwklH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726073AbgHICkX (ORCPT ); Sat, 8 Aug 2020 22:40:23 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:34605 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726058AbgHICkX (ORCPT ); Sat, 8 Aug 2020 22:40:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596940822; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7ZWmNdmE9mXz97K5KedK2xTYBcMa+8BCG/iCLTDYqd8=; b=SYWNwklHfN01WgxbnRqfxLU1SreQ/icXE2ndxkMjo9JSm3AoIwigHK1HOvx7OMYB7BJviW 7omVEgbSVu/SvWfZ5dW69RcLybILH4/iCF6fi4EATnH15qLW9Q6xiW7xyJMQIEy9uVL4fq Q80B2OM+KXwgKnHZnK/HqToyLWggyUg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-465-ZN91v3kLN4eIyNUc3Cyx1A-1; Sat, 08 Aug 2020 22:40:18 -0400 X-MC-Unique: ZN91v3kLN4eIyNUc3Cyx1A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 22B9459; Sun, 9 Aug 2020 02:40:17 +0000 (UTC) Received: from T590 (ovpn-12-63.pek2.redhat.com [10.72.12.63]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6F67E2C26B; Sun, 9 Aug 2020 02:40:10 +0000 (UTC) Date: Sun, 9 Aug 2020 10:40:05 +0800 From: Ming Lei To: Matthew Wilcox Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: Very slow qemu device access Message-ID: <20200809024005.GC2134904@T590> References: <20200807174416.GF17456@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200807174416.GF17456@casper.infradead.org> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello Matthew, On Fri, Aug 07, 2020 at 06:44:16PM +0100, Matthew Wilcox wrote: > > Everything starts going very slowly after this commit: > > commit 37f4a24c2469a10a4c16c641671bd766e276cf9f (refs/bisect/bad) > Author: Ming Lei > Date: Tue Jun 30 22:03:57 2020 +0800 > > blk-mq: centralise related handling into blk_mq_get_driver_tag Yeah, the above is one known bad commit, which is reverted in 4e2f62e566b5 ("Revert "blk-mq: put driver tag when this request is completed") Finally the fixed patch of 'blk-mq: centralise related handling into blk_mq_get_driver_tag' is merged as 568f27006577 ("blk-mq: centralise related handling into blk_mq_get_driver_tag"). So please test either 4e2f62e566b5 or 568f27006577 and see if there is such issue. Thanks, Ming