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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09E0CC433F5 for ; Wed, 13 Apr 2022 11:12:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235148AbiDMLOl (ORCPT ); Wed, 13 Apr 2022 07:14:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232227AbiDMLOi (ORCPT ); Wed, 13 Apr 2022 07:14:38 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3573027FE3; Wed, 13 Apr 2022 04:12:18 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id E1787210E5; Wed, 13 Apr 2022 11:12:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1649848336; h=from:from:reply-to: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=ngB0VaDZkffeOh+BSwJSCsqMcNibSRUO4jU8FKml6Bs=; b=i8qKj0NNFnGDs/62UlAmcsdLiT3oYBGGKRDyTKuXoGgeqCfro+kOFHFEtUEnkuXMb9nrfZ jsOai74lku4/r+dmPZLZkCSpMSx3PL33g3X0PyDW/EOZWGk9rEXFvoS8UkeuIHLitPT1b5 ViZOs9dic+cSfwyRWq1RVGDSWUAlQGw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1649848336; h=from:from:reply-to: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=ngB0VaDZkffeOh+BSwJSCsqMcNibSRUO4jU8FKml6Bs=; b=haFT45FMpnXW+0MzW9Ui1fMZNh/llnnI3l08AdD/0HoufaBvM07pNwAHzWzodylCXdQXTp kTc795IgiNJSZQBA== Received: from quack3.suse.cz (unknown [10.100.224.230]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id CCDB2A3B87; Wed, 13 Apr 2022 11:12:16 +0000 (UTC) Received: by quack3.suse.cz (Postfix, from userid 1000) id 7F4AFA0615; Wed, 13 Apr 2022 13:12:16 +0200 (CEST) Date: Wed, 13 Apr 2022 13:12:16 +0200 From: Jan Kara To: Yu Kuai Cc: tj@kernel.org, axboe@kernel.dk, paolo.valente@linaro.org, jack@suse.cz, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com Subject: Re: [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion Message-ID: <20220413111216.npgrdzaubsvjsmy3@quack3.lan> References: <20220305091205.4188398-1-yukuai3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220305091205.4188398-1-yukuai3@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat 05-03-22 17:11:54, Yu Kuai wrote: > Currently, bfq can't handle sync io concurrently as long as they > are not issued from root group. This is because > 'bfqd->num_groups_with_pending_reqs > 0' is always true in > bfq_asymmetric_scenario(). > > This patchset tries to support concurrent sync io if all the sync ios > are issued from the same cgroup: > > 1) Count root_group into 'num_groups_with_pending_reqs', patch 1-5; Seeing the complications and special casing for root_group I wonder: Won't we be better off to create fake bfq_sched_data in bfq_data and point root_group->sched_data there? AFAICS it would simplify the code considerably as root_group would be just another bfq_group, no need to special case it in various places, no games with bfqg->my_entity, etc. Paolo, do you see any problem with that? Honza -- Jan Kara SUSE Labs, CR