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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 768F5C32788 for ; Thu, 11 Oct 2018 10:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EEA120835 for ; Thu, 11 Oct 2018 10:15:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SeccW7tZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2EEA120835 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728001AbeJKRmP (ORCPT ); Thu, 11 Oct 2018 13:42:15 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:42870 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726008AbeJKRmP (ORCPT ); Thu, 11 Oct 2018 13:42:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=YG8UbBjfiExhO+KadlZzPriBJIjwKLYi+gzJnoeMQzc=; b=SeccW7tZGreQ14rP3ncbb/bDJ pZqgqGdGJld4Aft95148Xs3un62gsL3JmN6adtu0m3Fa6qWrRHBGiNhtGJdNiCe3oplZe5oRff2+S stYfVsAwr2Af6cZjHO9hW81sLeFZSMEhMjQdmNpYdozTKdIC1cPUr97bju4A0oSpHoU9IewYwieJp V2YPpqxuNkN0R7/QPi0NihtK0OC4nUnalGHovu1LqdlpXBqQIA81PX5SzHIYUDRhz8O+agYE0bzcj ipduHL5rZBW3cAy4n9KqKkc1yQBl+dqZGQhlOLlhJNGX0+Im3mEjzOYYLWBNJQB4kQ1M4FvKRy3IA sKyPwCUJQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gAY0E-0001HX-Fp; Thu, 11 Oct 2018 10:15:34 +0000 Date: Thu, 11 Oct 2018 03:15:34 -0700 From: Christoph Hellwig To: John Garry Cc: Christoph Hellwig , "Martin K. Petersen" , jejb@linux.vnet.ibm.com, linuxarm@huawei.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Ming Lei , chenxiang Subject: Re: [PATCH 0/7] hisi_sas: Misc bugfixes and an optimisation patch Message-ID: <20181011101534.GA31802@infradead.org> References: <1537801594-207139-1-git-send-email-john.garry@huawei.com> <20181011063603.GA3456@infradead.org> <118d01db-05f4-a85b-850c-c4e5a5616a16@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <118d01db-05f4-a85b-850c-c4e5a5616a16@huawei.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 11, 2018 at 10:59:11AM +0100, John Garry wrote: > > > blk-mq tags are always per-host (which has actually caused problems for > > ATA, which is now using its own per-device tags). > > > > So, for example, if Scsi_host.can_queue = 2048 and Scsi_host.nr_hw_queues = > 16, then rq tags are still in range [0, 2048) for that HBA, i.e. invariant > on queue count? Yes, if can_queue is 2048 you will gets tags from 0..2047. IFF you device needs different tags for different queues it can use the blk_mq_unique_tag heper to generate unique global tag. But unless you actuall have multiple hardware queues that latter part is rather irrelevant to start with.