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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 CE853C5DF60 for ; Thu, 7 Nov 2019 15:42:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97D9E21882 for ; Thu, 7 Nov 2019 15:42:26 +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="fBw9/3DF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729839AbfKGPm0 (ORCPT ); Thu, 7 Nov 2019 10:42:26 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:38742 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726810AbfKGPmZ (ORCPT ); Thu, 7 Nov 2019 10:42:25 -0500 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=cfQe+TqAPfiHi0Od9OyJixFH/1rtoMH2zyZ+3Zby/hE=; b=fBw9/3DFOgRSdfYbjn68RW2bB hrYxOrqcfd11KLjCTxjcx2IxvvNw1hywL//q3/3fZpseMQUDFmFIqbU/zRIQBGblYkv7iX2/5nGkB /w/zd9667oxMdM4jb/i7q0boVix8NNLnMmOIIH4LD4Zfnu+6mh9pR/9n0YLr0HH+X0R3iwHF4KnsB ed6b7+htv4rt6gbnKql0MnD2OLKq2UBlVyCePioS1eOP61fU254IAMXEPHFPd9vJQAyCsm4L0Q8tQ 59FXofOzb3fvO6Yoa5BYnSP4AtkXi7je/mB3O2MW+wIODOsqBtU29wbnV2rJkGA6uJe2j/7zFNiMM VUPE3r+wQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iSjvU-0006su-IA; Thu, 07 Nov 2019 15:42:24 +0000 Date: Thu, 7 Nov 2019 07:42:24 -0800 From: "hch@infradead.org" To: "Derrick, Jonathan" Cc: "hch@infradead.org" , "kbusch@kernel.org" , "lorenzo.pieralisi@arm.com" , "linux-pci@vger.kernel.org" , "helgaas@kernel.org" Subject: Re: [PATCH 0/3] PCI: vmd: Reducing tail latency by affining to the storage stack Message-ID: <20191107154224.GA26224@infradead.org> References: <1573040408-3831-1-git-send-email-jonathan.derrick@intel.com> <20191107093952.GA13826@infradead.org> <20191107153736.GA16006@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Nov 07, 2019 at 03:40:15PM +0000, Derrick, Jonathan wrote: > On Thu, 2019-11-07 at 07:37 -0800, hch@infradead.org wrote: > > On Thu, Nov 07, 2019 at 02:12:50PM +0000, Derrick, Jonathan wrote: > > > > How does this compare to simplify disabling VMD? > > > > > > It's a moot point since Keith pointed out a few flaws with this set, > > > however disabling VMD is not an option for users who wish to > > > passthrough VMD > > > > And why would you ever pass through vmd instead of the actual device? > > That just makes things go slower and adds zero value. > > Ability to use physical Root Ports/DSPs/etc in a guest. Slower is > acceptable for many users if it fits within a performance window What is the actual use case? What does it enable that otherwise doesn't work and is actually useful? And real use cases please and no marketing mumble jumble.