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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 BB8F2C43603 for ; Wed, 4 Dec 2019 10:24:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93AD92073C for ; Wed, 4 Dec 2019 10:24:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727351AbfLDKYg (ORCPT ); Wed, 4 Dec 2019 05:24:36 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:2154 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726899AbfLDKYg (ORCPT ); Wed, 4 Dec 2019 05:24:36 -0500 Received: from lhreml707-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 8B14B77D71B06C2BE9CD; Wed, 4 Dec 2019 10:24:35 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by lhreml707-cah.china.huawei.com (10.201.108.48) with Microsoft SMTP Server (TLS) id 14.3.408.0; Wed, 4 Dec 2019 10:24:35 +0000 Received: from [127.0.0.1] (10.202.226.46) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1713.5; Wed, 4 Dec 2019 10:24:35 +0000 Subject: Re: [PATCH 04/11] blk-mq: Facilitate a shared sbitmap per tagset To: Hannes Reinecke , "Martin K. Petersen" CC: Jens Axboe , Christoph Hellwig , "James Bottomley" , Ming Lei , , References: <20191202153914.84722-1-hare@suse.de> <20191202153914.84722-5-hare@suse.de> <5beb7d51-500e-5bda-4e46-8414fd8b64ff@suse.de> From: John Garry Message-ID: <6c8b8676-a3c7-6fd5-3b6d-c0b469c80756@huawei.com> Date: Wed, 4 Dec 2019 10:24:34 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <5beb7d51-500e-5bda-4e46-8414fd8b64ff@suse.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.202.226.46] X-ClientProxiedBy: lhreml702-chm.china.huawei.com (10.201.108.51) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 03/12/2019 15:02, Hannes Reinecke wrote: >>> +     */ >> If you don't have a shared sched bitmap - which I didn't think we needed >> - then all we need is a simple sbitmap_queue_resize(&tagset->__bitmap_tags) >> >> Otherwise it's horrible to resize shared sched bitmaps... >> > Resizing shared sched bitmaps is done in patch 6/11. > General idea is to move the scheduler bitmap into the request queue > (well, actually the elevator), as this gives us a per-request_queue > bitmap. Which is actually what we want here, as the scheduler will need > to look at all requests, hence needing to access to the same bitmap. > And it also gives us an easy way of resizing the sched tag bitmap, as > then we can resize the bitmap on a per-queue basis, and leave the > underlying tagset bitmap untouched. OK, but I am just concerned if that is really required in this series and whether it is just another obstacle to getting it accepted. Thanks, John > > [ .. ] >>> diff --git a/block/blk-mq.h b/block/blk-mq.h >>> index 78d38b5f2793..4c1ea206d3f4 100644 >>> --- a/block/blk-mq.h >>> +++ b/block/blk-mq.h