From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41kjPZ2m6rzF3HK for ; Tue, 7 Aug 2018 02:13:38 +1000 (AEST) 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 In-Reply-To: <20180806161040.GA4675@infradead.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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