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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 111C6C433B4 for ; Wed, 7 Apr 2021 08:07:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CB69C61222 for ; Wed, 7 Apr 2021 08:07:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236643AbhDGIHJ (ORCPT ); Wed, 7 Apr 2021 04:07:09 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2779 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233970AbhDGIHJ (ORCPT ); Wed, 7 Apr 2021 04:07:09 -0400 Received: from fraeml737-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FFcHy74fYz6873F; Wed, 7 Apr 2021 15:59:58 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml737-chm.china.huawei.com (10.206.15.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Wed, 7 Apr 2021 10:06:58 +0200 Received: from [10.210.168.126] (10.210.168.126) 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 15.1.2106.2; Wed, 7 Apr 2021 09:06:57 +0100 Subject: Re: [PATCH] blk-mq: set default elevator as deadline in case of hctx shared tagset To: Ming Lei CC: Jens Axboe , , Yanhui Ma , Hannes Reinecke , Kashyap Desai References: <20210406031933.767228-1-ming.lei@redhat.com> From: John Garry Message-ID: <6c346805-a7b1-f66d-af16-b1da03d77fc0@huawei.com> Date: Wed, 7 Apr 2021 09:04:30 +0100 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: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.210.168.126] X-ClientProxiedBy: lhreml703-chm.china.huawei.com (10.201.108.52) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Reviewed-by: John Garry > On Tue, Apr 06, 2021 at 11:25:08PM +0100, John Garry wrote: >> On 06/04/2021 04:19, Ming Lei wrote: >> >> Hi Ming, >> >>> Yanhui found that write performance is degraded a lot after applying >>> hctx shared tagset on one test machine with megaraid_sas. And turns out >>> it is caused by none scheduler which becomes default elevator caused by >>> hctx shared tagset patchset. >>> >>> Given more scsi HBAs will apply hctx shared tagset, and the similar >>> performance exists for them too. >>> >>> So keep previous behavior by still using default mq-deadline for queues >>> which apply hctx shared tagset, just like before. >> I think that there a some SCSI HBAs which have nr_hw_queues > 1 and don't >> use shared sbitmap - do you think that they want want this as well (without >> knowing it)? > I don't know but none has been used for them since the beginning, so not > an regression of shared tagset, but this one is really. It seems fine to revert to previous behavior when host_tagset is set. I didn't check the results for this recently, but for the original shared tagset patchset [0] I had: none sched: 2132K IOPS mq-deadline sched: 2145K IOPS A quick audit of other SCSI HBA drivers in drivers/scsi which set nr_hw_queues and don't set host_tagset gives lpfc, qla2xxx, qedi (nr_hw_queues seems to be getting unset), storvsc_drv (host_tagset might be getting set), virtio_scsi, and then mpi3mr Thanks, John [0] https://lore.kernel.org/linux-scsi/1597850436-116171-1-git-send-email-john.garry@huawei.com/