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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 1EAF0C0650F for ; Mon, 5 Aug 2019 13:52:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F136A2086D for ; Mon, 5 Aug 2019 13:52:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729201AbfHENwH (ORCPT ); Mon, 5 Aug 2019 09:52:07 -0400 Received: from mga06.intel.com ([134.134.136.31]:18172 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728662AbfHENwH (ORCPT ); Mon, 5 Aug 2019 09:52:07 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Aug 2019 06:51:39 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,350,1559545200"; d="scan'208";a="178854881" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga006.jf.intel.com with ESMTP; 05 Aug 2019 06:51:38 -0700 Date: Mon, 5 Aug 2019 07:49:07 -0600 From: Keith Busch To: Benjamin Herrenschmidt Cc: Keith Busch , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Paul Pawlowski , Jens Axboe , Christoph Hellwig , Minwoo Im , Damien Le Moal Subject: Re: [PATCH v3] nvme-pci: Support shared tags across queues for Apple 2018 controllers Message-ID: <20190805134907.GC18647@localhost.localdomain> References: <20190730153044.GA13948@localhost.localdomain> <2030a028664a9af9e96fffca3ab352faf1f739e5.camel@kernel.crashing.org> <6290507e1b2830b1729fc858cd5c20b85d092728.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6290507e1b2830b1729fc858cd5c20b85d092728.camel@kernel.crashing.org> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 05, 2019 at 04:49:23PM +1000, Benjamin Herrenschmidt wrote: > On Tue, 2019-07-30 at 13:28 -0700, Benjamin Herrenschmidt wrote: > > > One problem is that we've an nvme parameter, io_queue_depth, that a user > > > could set to something less than 32, and then you won't be able to do > > > any IO. I'd recommend enforce the admin queue to QD1 for this device so > > > that you have more potential IO tags. > > > > So I had a look and it's not that trivial. I would have to change > > a few things that use constants for the admin queue depth, such as > > the AEN tag etc... > > > > For such a special case, I am tempted instead to do the much simpler: > > > > if (dev->ctrl.quirks & NVME_QUIRK_SHARED_TAGS) { > > if (dev->q_depth < (NVME_AQ_DEPTH + 2)) > > dev->q_depth = NVME_AQ_DEPTH + 2; > > } > > > > In nvme_pci_enable() next to the existing q_depth hackery for other > > controllers. > > > > Thoughts ? > > Ping ? I had another look today and I don't feel like mucking around > with all the AQ size logic, AEN magic tag etc... just for that sake of > that Apple gunk. I'm happy to have it give up IO tags, it doesn't seem > to make much of a difference in practice anyway. > > But if you feel strongly about it, then I'll implement the "proper" way > sometimes this week, adding a way to shrink the AQ down to something > like 3 (one admin request, one async event (AEN), and the empty slot) > by making a bunch of the constants involved variables instead. I don't feel too strongly about it. I think your patch is fine, so Acked-by: Keith Busch