From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0pAL-00054J-EN for qemu-devel@nongnu.org; Tue, 27 Mar 2018 10:01:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f0pAF-0007YE-Ek for qemu-devel@nongnu.org; Tue, 27 Mar 2018 10:01:33 -0400 Received: from mga14.intel.com ([192.55.52.115]:52835) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f0pAF-0007XX-5M for qemu-devel@nongnu.org; Tue, 27 Mar 2018 10:01:27 -0400 Date: Tue, 27 Mar 2018 21:59:49 +0800 From: Tiwei Bie Message-ID: <20180327135949.owjzqtbrnlfmj6yd@debian> References: <20180319071537.28649-1-tiwei.bie@intel.com> <20180319071537.28649-7-tiwei.bie@intel.com> <20180322171740-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180322171740-mutt-send-email-mst@kernel.org> Subject: Re: [Qemu-devel] [PATCH v2 6/6] vhost-user: add VFIO based accelerators support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, alex.williamson@redhat.com, jasowang@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, cunming.liang@intel.com, dan.daly@intel.com, jianfeng.tan@intel.com, zhihong.wang@intel.com, xiao.w.wang@intel.com On Thu, Mar 22, 2018 at 06:19:44PM +0200, Michael S. Tsirkin wrote: > On Mon, Mar 19, 2018 at 03:15:37PM +0800, Tiwei Bie wrote: [...] > > > > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt > > index cb3a7595aa..264a58a800 100644 > > --- a/docs/interop/vhost-user.txt > > +++ b/docs/interop/vhost-user.txt [...] > > > The accelerator > > +context will be set for each queue independently. So the page-per-vq property > > +should also be enabled. > > Backend author is unlikely to know what does page-per-vq property mean. > > Is this intended for users maybe? docs/interop is not the best place > for user-facing documentation. > > I also wonder: > > commit d9997d89a4a09a330a056929d06d4b7b0b7a8239 > Author: Marcel Apfelbaum > Date: Wed Sep 7 18:02:25 2016 +0300 > > virtio-pci: reduce modern_mem_bar size > > Currently each VQ Notification Virtio Capability is allocated > on a different page. The idea is to enable split drivers within > guests, however there are no known plans to do that. > The allocation will result in a 8MB BAR, more than various > guest firmwares pre-allocates for PCI Bridges hotplug process. > > looks like enabling page per vq will break pci express hotplug. > I suspect more work is needed to down-size the BAR to # of VQs > actually supported. > I agree. Maybe we can fix the potential pci express hotplug issue caused by enabling page-per-vq in another patch set. Best regards, Tiwei Bie From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-3656-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [66.179.20.138]) by lists.oasis-open.org (Postfix) with ESMTP id BF19058180F8 for ; Tue, 27 Mar 2018 07:01:37 -0700 (PDT) Date: Tue, 27 Mar 2018 21:59:49 +0800 From: Tiwei Bie Message-ID: <20180327135949.owjzqtbrnlfmj6yd@debian> References: <20180319071537.28649-1-tiwei.bie@intel.com> <20180319071537.28649-7-tiwei.bie@intel.com> <20180322171740-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180322171740-mutt-send-email-mst@kernel.org> Subject: [virtio-dev] Re: [PATCH v2 6/6] vhost-user: add VFIO based accelerators support To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, alex.williamson@redhat.com, jasowang@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, cunming.liang@intel.com, dan.daly@intel.com, jianfeng.tan@intel.com, zhihong.wang@intel.com, xiao.w.wang@intel.com List-ID: On Thu, Mar 22, 2018 at 06:19:44PM +0200, Michael S. Tsirkin wrote: > On Mon, Mar 19, 2018 at 03:15:37PM +0800, Tiwei Bie wrote: [...] > > > > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt > > index cb3a7595aa..264a58a800 100644 > > --- a/docs/interop/vhost-user.txt > > +++ b/docs/interop/vhost-user.txt [...] > > > The accelerator > > +context will be set for each queue independently. So the page-per-vq property > > +should also be enabled. > > Backend author is unlikely to know what does page-per-vq property mean. > > Is this intended for users maybe? docs/interop is not the best place > for user-facing documentation. > > I also wonder: > > commit d9997d89a4a09a330a056929d06d4b7b0b7a8239 > Author: Marcel Apfelbaum > Date: Wed Sep 7 18:02:25 2016 +0300 > > virtio-pci: reduce modern_mem_bar size > > Currently each VQ Notification Virtio Capability is allocated > on a different page. The idea is to enable split drivers within > guests, however there are no known plans to do that. > The allocation will result in a 8MB BAR, more than various > guest firmwares pre-allocates for PCI Bridges hotplug process. > > looks like enabling page per vq will break pci express hotplug. > I suspect more work is needed to down-size the BAR to # of VQs > actually supported. > I agree. Maybe we can fix the potential pci express hotplug issue caused by enabling page-per-vq in another patch set. Best regards, Tiwei Bie --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org