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 2F71DC433FE for ; Mon, 29 Nov 2021 19:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350175AbhK2TVS (ORCPT ); Mon, 29 Nov 2021 14:21:18 -0500 Received: from m43-7.mailgun.net ([69.72.43.7]:23634 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380066AbhK2TTS (ORCPT ); Mon, 29 Nov 2021 14:19:18 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1638213360; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: From: References: Cc: To: Subject: MIME-Version: Date: Message-ID: Sender; bh=RScI3Hhu2IHWULTsGJc57d5MH8nBdwIsssHjRze0B6U=; b=g0rZGCFWJ+G7LNM1DlQcPS4pQTYnn9K9jVUB7MN3ZxHrQcvIJCNht0dhaiTJroCYwLcjh444 EC7Inq3/ngqEAQQFXZFznCWuwnPkQugmFWX31rf21uU1iDfGPjMe1Zv5hiUKVhdsg0qKbSET 0Cz+Q5i/Zq20HUh7RXR2brth/IM= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyJlNmU5NiIsICJsaW51eC1zY3NpQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n07.prod.us-east-1.postgun.com with SMTP id 61a526ef6bacc185a5c1db81 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 29 Nov 2021 19:15:59 GMT Sender: asutoshd=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 61AD5C4314E; Mon, 29 Nov 2021 19:15:58 +0000 (UTC) Received: from [192.168.1.3] (cpe-66-27-70-157.san.res.rr.com [66.27.70.157]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: asutoshd) by smtp.codeaurora.org (Postfix) with ESMTPSA id 763CEC43637; Mon, 29 Nov 2021 19:15:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 smtp.codeaurora.org 763CEC43637 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=codeaurora.org Message-ID: <2288f0b8-fa55-2020-b210-b5e7d06d6a4b@codeaurora.org> Date: Mon, 29 Nov 2021 11:15:53 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH 03/15] scsi: implement reserved command handling To: Hannes Reinecke , "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , linux-scsi@vger.kernel.org, John Garry , Bart van Assche References: <20211125151048.103910-1-hare@suse.de> <20211125151048.103910-4-hare@suse.de> From: "Asutosh Das (asd)" In-Reply-To: <20211125151048.103910-4-hare@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 11/25/2021 7:10 AM, Hannes Reinecke wrote: > Quite some drivers are using management commands internally, which > typically use the same hardware tag pool (ie they are being allocated > from the same hardware resources) as the 'normal' I/O commands. > These commands are set aside before allocating the block-mq tag bitmap, > so they'll never show up as busy in the tag map. > The block-layer, OTOH, already has 'reserved_tags' to handle precisely > this situation. > So this patch adds a new field 'nr_reserved_cmds' to the SCSI host > template to instruct the block layer to set aside a tag space for these > management commands by using reserved tags. > > Signed-off-by: Hannes Reinecke > --- Reviewed-by: Asutosh Das > drivers/scsi/hosts.c | 3 +++ > drivers/scsi/scsi_lib.c | 9 ++++++++- > include/scsi/scsi_host.h | 22 +++++++++++++++++++++- > 3 files changed, 32 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index a539fa2fb221..8ee7a7279b6b 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -482,6 +482,9 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) > if (sht->virt_boundary_mask) > shost->virt_boundary_mask = sht->virt_boundary_mask; > > + if (sht->nr_reserved_cmds) > + shost->nr_reserved_cmds = sht->nr_reserved_cmds; > + > device_initialize(&shost->shost_gendev); > dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); > shost->shost_gendev.bus = &scsi_bus_type; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 6fbd36c9c416..e8f1025d0ed8 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1939,7 +1939,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) > tag_set->ops = &scsi_mq_ops_no_commit; > tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; > tag_set->nr_maps = shost->nr_maps ? : 1; > - tag_set->queue_depth = shost->can_queue; > + tag_set->queue_depth = > + shost->can_queue + shost->nr_reserved_cmds; > + tag_set->reserved_tags = shost->nr_reserved_cmds; > tag_set->cmd_size = cmd_size; > tag_set->numa_node = NUMA_NO_NODE; > tag_set->flags = BLK_MQ_F_SHOULD_MERGE; > @@ -1964,6 +1966,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) > * @nowait: do not wait for command allocation to succeed. > * > * Allocates a SCSI command for internal LLDD use. > + * If 'nr_reserved_commands' is spectified by the host the > + * command will be allocated from the reserved tag pool; > + * otherwise the normal tag pool will be used. > */ > struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > int data_direction, bool nowait) > @@ -1973,6 +1978,8 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > blk_mq_req_flags_t flags = 0; > int op; > > + if (sdev->host->nr_reserved_cmds) > + flags |= BLK_MQ_REQ_RESERVED; > if (nowait) > flags |= BLK_MQ_REQ_NOWAIT; > op = (data_direction == DMA_TO_DEVICE) ? > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 6f49a8940dc4..7512d97aceb4 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -367,10 +367,19 @@ struct scsi_host_template { > /* > * This determines if we will use a non-interrupt driven > * or an interrupt driven scheme. It is set to the maximum number > - * of simultaneous commands a single hw queue in HBA will accept. > + * of simultaneous commands a single hw queue in HBA will accept > + * excluding internal commands. > */ > int can_queue; > > + /* > + * This determines how many commands the HBA will set aside > + * for internal commands. This number will be added to > + * @can_queue to calcumate the maximum number of simultaneous > + * commands sent to the host. > + */ > + int nr_reserved_cmds; > + > /* > * In many instances, especially where disconnect / reconnect are > * supported, our host also has an ID on the SCSI bus. If this is > @@ -608,6 +617,11 @@ struct Scsi_Host { > unsigned short max_cmd_len; > > int this_id; > + > + /* > + * Number of commands this host can handle at the same time. > + * This excludes reserved commands as specified by nr_reserved_cmds. > + */ > int can_queue; > short cmd_per_lun; > short unsigned int sg_tablesize; > @@ -626,6 +640,12 @@ struct Scsi_Host { > */ > unsigned nr_hw_queues; > unsigned nr_maps; > + > + /* > + * Number of reserved commands to allocate, if any. > + */ > + unsigned nr_reserved_cmds; > + > unsigned active_mode:2; > > /* > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project