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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 4886DC46471 for ; Mon, 6 Aug 2018 16:13:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9D33208AF for ; Mon, 6 Aug 2018 16:13:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9D33208AF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733206AbeHFSXZ (ORCPT ); Mon, 6 Aug 2018 14:23:25 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:37906 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730876AbeHFSXY (ORCPT ); Mon, 6 Aug 2018 14:23:24 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 27E8A40241DA; Mon, 6 Aug 2018 16:13:36 +0000 (UTC) Received: from redhat.com (unknown [10.36.118.7]) by smtp.corp.redhat.com (Postfix) with SMTP id 765111C589; Mon, 6 Aug 2018 16:13:33 +0000 (UTC) Date: Mon, 6 Aug 2018 19:13:32 +0300 From: "Michael S. Tsirkin" To: Christoph Hellwig Cc: Anshuman Khandual , Benjamin Herrenschmidt , robh@kernel.org, srikar@linux.vnet.ibm.com, aik@ozlabs.ru, Jason Wang , linuxram@us.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, paulus@samba.org, joe@perches.com, david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Message-ID: <20180806191111-mutt-send-email-mst@kernel.org> References: <20180802235332-mutt-send-email-mst@kernel.org> <20180803220812-mutt-send-email-mst@kernel.org> <01c74680c4b3aa25d9b4375a9ab5e10046b7c71b.camel@kernel.crashing.org> <20180805032355-mutt-send-email-mst@kernel.org> <74a1e1b8-81e0-84db-6d0d-d8bd9caebb4a@linux.vnet.ibm.com> <20180806163440-mutt-send-email-mst@kernel.org> <20180806152406.GA29020@infradead.org> <20180806190321-mutt-send-email-mst@kernel.org> <20180806161040.GA4675@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180806161040.GA4675@infradead.org> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 06 Aug 2018 16:13:36 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 06 Aug 2018 16:13:36 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mst@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 06, 2018 at 09:10:40AM -0700, Christoph Hellwig wrote: > On Mon, Aug 06, 2018 at 07:06:05PM +0300, Michael S. Tsirkin wrote: > > > I've done something very similar in the thread I posted a few years > > > ago. > > > > Right so that was before spectre where a virtual call was cheaper :( > > Sorry, I meant days, not years. The whole point of the thread was the > slowdowns due to retpolines, which are the software spectre mitigation. Oh that makes sense then. Could you post a pointer pls so this patchset is rebased on top (there are things to change about 4/4 but 1-3 could go in if they don't add overhead)? -- MST