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 DD5B8C4332F for ; Thu, 24 Nov 2022 01:18:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229625AbiKXBSB (ORCPT ); Wed, 23 Nov 2022 20:18:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229673AbiKXBR7 (ORCPT ); Wed, 23 Nov 2022 20:17:59 -0500 Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8368A27B07; Wed, 23 Nov 2022 17:17:56 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4NHg8v0M6Rz4f3v6w; Thu, 24 Nov 2022 09:17:51 +0800 (CST) Received: from [10.174.176.73] (unknown [10.174.176.73]) by APP4 (Coremail) with SMTP id gCh0CgD3GthAxn5jsBE0BA--.21372S3; Thu, 24 Nov 2022 09:17:53 +0800 (CST) Subject: Re: nbd: please don't spawn 16 threads when nbd is not even in use To: Pavel Machek , Eric Blake Cc: kernel list , josef@toxicpanda.com, linux-block@vger.kernel.org, nbd@other.debian.org, "yukuai (C)" References: <20221123200845.cuct5euvikqksojm@redhat.com> From: Yu Kuai Message-ID: Date: Thu, 24 Nov 2022 09:17:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: gCh0CgD3GthAxn5jsBE0BA--.21372S3 X-Coremail-Antispam: 1UD129KBjvdXoW7GFy8WrWfWFyftrWfZFyxXwb_yoW3AFX_WF W7ZFyDGw4UXF18Ja1qkF1rWFW8Xrs7XF4jqasxtwsrJw43W3s3uF4DWry3Zw4UGw4YyFnx ur1UZay7Ar47ujkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbzAYFVCjjxCrM7AC8VAFwI0_Gr0_Xr1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwV A0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x02 67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lc7I2V7IY0VAS07AlzVAYIcxG8wCF04k20xvY0x0E wIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E74 80Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcVC0 I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04 k26cxKx2IYs7xG6rW3Jr0E3s1lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY 1x0267AKxVWUJVW8JbIYCTnIWIevJa73UjIFyTuYvjxUrR6zUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi, 在 2022/11/24 6:01, Pavel Machek 写道: > Hi! > >>> I see this... and it looks like there are 16 workqueues before nbd is >>> even used. Surely there are better ways to do that? >> >> Yes, it would be nice to create a pool of workers that only spawns up >> threads when actual parallel requests are made. Are you willing to >> help write the patch? > > I was thinking more "only spawn a workqueue when nbd is opened" or so. > > I have 16 of them, and I'm not using nbd. Workqueue per open device is > okay, current situation... not so much. You can take a look at this commit: e2daec488c57 ("nbd: Fix hungtask when nbd_config_put") Allocation of recv_workq is moved from start device to alloc device to fix hungtask. You might need to be careful if you want to move this. Thanks, Kuai > > Pavel >