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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5D4DC433F5 for ; Sat, 19 Feb 2022 07:38:32 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4K10mQ4kjNz3cbs for ; Sat, 19 Feb 2022 18:38:30 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=KsxrcfYa; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=bombadil.srs.infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=batv+89c436a5482820edb7f2+6754+infradead.org+hch@bombadil.srs.infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=KsxrcfYa; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4K10ld51sRz3bP1 for ; Sat, 19 Feb 2022 18:37:44 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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; bh=h57KiAEVSKkzXdNc8Dx5lCWM++DN28M84mRcDiV5fkY=; b=KsxrcfYaerfj7S4ITWFvQAQ0x6 24aeSlzHZ3cmMdzzDJjwD5MH7BiCBtomrZK+sUouoLD9vIJHuUOIq8hNC2rT9TREsjqowo7ZigLPU llG/bACQNWJM62cm7Wc1o0o5yl4BeuJOK1InpRSg6F2nlLE+wMwB6Sr0Gv2APOv6ZKnh4XB2/bx0q pO/NM0jEjfo63HNdo4QypAR7fM098sBkqtoJnexaTDGT2EC9VuGERlxc6rMnA1xJW3+p1h+TLVuCS Lhtn1UlZlZPW5MAURTUYVTtlIOcC7djUDixNNJ6pg7uXqJlAMgXvaRfk2N49sHxK0dt49GFiuTp9+ u3rD/Uaw==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nLKIh-00GNfs-Pt; Sat, 19 Feb 2022 07:37:03 +0000 Date: Fri, 18 Feb 2022 23:37:03 -0800 From: Christoph Hellwig To: "Melanie Plageman (Microsoft)" Subject: Re: [PATCH RFC v1 0/5] Add SCSI per device tagsets Message-ID: References: <20220218184157.176457-1-melanieplageman@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220218184157.176457-1-melanieplageman@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tyreld@linux.ibm.com, linux-hyperv@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, mikelley@microsoft.com, R-QLogic-Storage-Upstream@marvell.com, paulus@samba.org, kys@microsoft.com, wei.liu@kernel.org, sthemmin@microsoft.com, linux-scsi@vger.kernel.org, sathya.prakash@broadcom.com, decui@microsoft.com, kashyap.desai@broadcom.com, njavali@marvell.com, MPT-FusionLinux.pdl@broadcom.com, haiyangz@microsoft.com, mpi3mr-linuxdrv.pdl@broadcom.com, suganath-prabu.subramani@broadcom.com, jejb@linux.ibm.com, john.garry@huawei.com, stefanha@redhat.com, storagedev@microchip.com, virtualization@lists.linux-foundation.org, megaraidlinux.pdl@broadcom.com, sreekanth.reddy@broadcom.com, martin.petersen@oracle.com, shivasharan.srikanteshwara@broadcom.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, sumit.saxena@broadcom.com, andres@anarazel.de, pbonzini@redhat.com, don.brace@microchip.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Feb 18, 2022 at 06:41:52PM +0000, Melanie Plageman (Microsoft) wrote: > Currently a single blk_mq_tag_set is associated with a Scsi_Host. When SCSI > controllers are limited, attaching multiple devices to the same controller is > required. In cloud environments with relatively high latency persistent storage, > requiring all devices on a controller to share a single blk_mq_tag_set > negatively impacts performance. So add more controllers instead of completely breaking the architecture.