Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932497Ab1ERApZ (ORCPT ); Tue, 17 May 2011 20:45:25 -0400 Received: from ozlabs.org ([203.10.76.45]:35184 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932107Ab1ERApY (ORCPT ); Tue, 17 May 2011 20:45:24 -0400 From: Rusty Russell To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Carsten Otte , Christian Borntraeger , linux390@de.ibm.com, Martin Schwidefsky , Heiko Carstens , Shirley Ma , lguest@lists.ozlabs.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, Krishna Kumar , Tom Lendacky , steved@us.ibm.com, habanero@linux.vnet.ibm.com Subject: Re: [PATCH 09/18] virtio: use avail_event index In-Reply-To: <20110517061031.GC26989@redhat.com> References: <8bba6a0a8eee17e741c5155b04ff1b1c9f34bf94.1304541919.git.mst@redhat.com> <874o54h4rt.fsf@rustcorp.com.au> <20110515135541.GF24932@redhat.com> <87ei3zdsq2.fsf@rustcorp.com.au> <20110517061031.GC26989@redhat.com> User-Agent: Notmuch/0.5 (http://notmuchmail.org) Emacs/23.2.1 (i686-pc-linux-gnu) Date: Wed, 18 May 2011 09:49:42 +0930 Message-ID: <87tycsn9lt.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 30 On Tue, 17 May 2011 09:10:31 +0300, "Michael S. Tsirkin" wrote: > Well one can imagine a driver doing: > > while (virtqueue_get_buf()) { > virtqueue_add_buf() > } > virtqueue_kick() > > which looks sensible (batch kicks) but might > process any number of bufs between kicks. No, we currently only expose the buffers in the kick, so it can only fill the ring doing that. We could change that (and maybe that's worth looking at)... > If we look at drivers closely enough, I think none > of them do the equivalent of the above, but not 100% sure. I'm pretty sure we don't have this kind of 'echo' driver yet. Drivers tend to take OS requests and queue them. The only one which does anything even partially sophisticated is the net driver... Thanks, 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/