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=-2.5 required=3.0 tests=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 23FA6C04EB8 for ; Fri, 30 Nov 2018 14:43:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E0DCB20863 for ; Fri, 30 Nov 2018 14:43:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0DCB20863 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726685AbeLABwq (ORCPT ); Fri, 30 Nov 2018 20:52:46 -0500 Received: from mga04.intel.com ([192.55.52.120]:11407 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726645AbeLABwq (ORCPT ); Fri, 30 Nov 2018 20:52:46 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Nov 2018 06:43:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,298,1539673200"; d="scan'208";a="108580214" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by FMSMGA003.fm.intel.com with ESMTP; 30 Nov 2018 06:43:14 -0800 Date: Fri, 30 Nov 2018 07:40:20 -0700 From: Keith Busch To: Christoph Hellwig Cc: Jens Axboe , Sagi Grimberg , Max Gurtovoy , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" Subject: Re: [PATCH 01/13] block: move queues types to the block layer Message-ID: <20181130144020.GH9377@localhost.localdomain> References: <20181129191310.9795-1-hch@lst.de> <20181129191310.9795-2-hch@lst.de> <20181129201914.GB9377@localhost.localdomain> <20181130080013.GB18936@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181130080013.GB18936@lst.de> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Nov 30, 2018 at 12:00:13AM -0800, Christoph Hellwig wrote: > On Thu, Nov 29, 2018 at 01:19:14PM -0700, Keith Busch wrote: > > On Thu, Nov 29, 2018 at 08:12:58PM +0100, Christoph Hellwig wrote: > > > +enum hctx_type { > > > + HCTX_TYPE_DEFAULT, /* all I/O not otherwise accounted for */ > > > + HCTX_TYPE_READ, /* just for READ I/O */ > > > + HCTX_TYPE_POLL, /* polled I/O of any kind */ > > > + > > > + HCTX_MAX_TYPES, > > > }; > > > > Well, there goes my plan to use this with Weighted-Round-Robin NVMe IO > > queues! > > Wo between what do you even want to round robin? If it is between > reads and writes that's easy. If we want priority reads or writes > (separate from polling) that's also still fairly easily. I was considering the IOPRIO_PRIO_CLASS. There are four of them, which may roughly correspond to the four NVMe IO queues weights. Maybe even through HIPRI flagged IOs with the RT class. > Btw, one thing I wanted to try once I get hold of the right hardware > is to mark the poll queues as priority queues and see if that makes > any differents in poll IOPS/latency. I doubt it will make much difference in IOPS, but should improve latency on hipri IOs at the expense of normal IO since hipri will be fetched ahead during command arbitrarion.