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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 48EAEC432C0 for ; Wed, 20 Nov 2019 06:36:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 138052245B for ; Wed, 20 Nov 2019 06:36:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QUe9rfAm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727165AbfKTGgJ (ORCPT ); Wed, 20 Nov 2019 01:36:09 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:56870 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726685AbfKTGgJ (ORCPT ); Wed, 20 Nov 2019 01:36:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574231767; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hsXkh/VQI3KB8Zl4hHKe473v7riRmv/Z4J6X27T5pmM=; b=QUe9rfAmppkJgxvhdrcdMU7NgM/qdYNMed76LaRZUbqoAXZJjGwP2s1ePb5h9zDwnHdIJ1 zzfbgv2Vc0rTTFkIzD4wafmxIEducxnbGjJy9imI6UYwVGIydnm6oIaHh7NB5nk++Rfe27 JmbYW1AZSpnNJu+78/HCvTwdasCAY2k= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-67-TZ6SJJfHPPCktfDD586oLw-1; Wed, 20 Nov 2019 01:36:04 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 60D021005500; Wed, 20 Nov 2019 06:36:02 +0000 (UTC) Received: from ming.t460p (ovpn-8-21.pek2.redhat.com [10.72.8.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 78B055C1B2; Wed, 20 Nov 2019 06:35:55 +0000 (UTC) Date: Wed, 20 Nov 2019 14:35:50 +0800 From: Ming Lei To: James Smart Cc: Sagi Grimberg , Jens Axboe , linux-block@vger.kernel.org, Keith Busch , linux-nvme@lists.infradead.org, Christoph Hellwig Subject: Re: [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request Message-ID: <20191120063550.GA3664@ming.t460p> References: <20191115104238.15107-1-ming.lei@redhat.com> <8f4402a0-967d-f12d-2f1a-949e1dda017c@grimberg.me> <20191116071754.GB18194@ming.t460p> <016afdbc-9c63-4193-e64b-aad91ba5fcc1@grimberg.me> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: TZ6SJJfHPPCktfDD586oLw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Nov 19, 2019 at 09:56:45AM -0800, James Smart wrote: > On 11/18/2019 4:05 PM, Sagi Grimberg wrote: > >=20 > > This is a much simpler fix that does not create this churn local to > > every driver. Also, I don't like the assumptions about tag reservations > > that the drivers is taking locally (that the connect will have tag 0 > > for example). All this makes this look like a hack. >=20 > Agree with Sagi on this last statement. When I reviewed the patch, it was > very non-intuitive. Why dependency on tag 0, why a queue number squirrell= ed > away on this one request only. Why change the initialization (queue point= er) > on this one specific request from its hctx and so on. For someone without > the history, ugly. >=20 > >=20 > > I'm starting to think we maybe need to get the connect out of the block > > layer execution if its such a big problem... Its a real shame if that i= s > > the case... >=20 > Yep. This is starting to be another case of perhaps I should be changing > nvme-fc's blk-mq hctx to nvme queue relationship in a different manner.= =A0 I'm > having a very hard time with all the queue resources today's policy is > wasting on targets. Wrt. the above two points, I believe both are not an issue at all by this driver specific approach, see my comment: https://lore.kernel.org/linux-block/fda43a50-a484-dde7-84a1-94ccf9346bdd@br= oadcom.com/T/#mb72afa6ed93bc852ca266779977634cf6214b329 Thanks, Ming