Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752004AbaJOGeC (ORCPT ); Wed, 15 Oct 2014 02:34:02 -0400 Received: from ozlabs.org ([103.22.144.67]:45941 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbaJOGcs (ORCPT ); Wed, 15 Oct 2014 02:32:48 -0400 From: Rusty Russell To: Jason Wang , mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org, kvm@vger.kernel.org, Jason Wang Subject: Re: [PATCH net-next RFC 1/3] virtio: support for urgent descriptors In-Reply-To: <1413011806-3813-2-git-send-email-jasowang@redhat.com> References: <1413011806-3813-1-git-send-email-jasowang@redhat.com> <1413011806-3813-2-git-send-email-jasowang@redhat.com> User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu) Date: Wed, 15 Oct 2014 16:10:02 +1030 Message-ID: <877g01c2ml.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jason Wang writes: > Below should be useful for some experiments Jason is doing. > I thought I'd send it out for early review/feedback. > > event idx feature allows us to defer interrupts until > a specific # of descriptors were used. > Sometimes it might be useful to get an interrupt after > a specific descriptor, regardless. > This adds a descriptor flag for this, and an API > to create an urgent output descriptor. > This is still an RFC: > we'll need a feature bit for drivers to detect this, > but we've run out of feature bits for virtio 0.X. > For experimentation purposes, drivers can assume > this is set, or add a driver-specific feature bit. > > Signed-off-by: Michael S. Tsirkin > Signed-off-by: Jason Wang The new VRING_DESC_F_URGENT bit is theoretically nicer, but for networking (which tends to take packets in order) couldn't we just set the event counter to give us a tx interrupt at the packet we want? Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/