From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751819Ab1EYEk7 (ORCPT ); Wed, 25 May 2011 00:40:59 -0400 Received: from ozlabs.org ([203.10.76.45]:44628 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751347Ab1EYEk4 (ORCPT ); Wed, 25 May 2011 00:40:56 -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: [PATCHv2 10/14] virtio_net: limit xmit polling In-Reply-To: <20110523111900.GB27212@redhat.com> References: <877h9kvlps.fsf@rustcorp.com.au> <20110522121008.GA12155@redhat.com> <87boyutbjg.fsf@rustcorp.com.au> <20110523111900.GB27212@redhat.com> User-Agent: Notmuch/0.5 (http://notmuchmail.org) Emacs/23.2.1 (i686-pc-linux-gnu) Date: Wed, 25 May 2011 11:05:04 +0930 Message-ID: <8739k3k1fb.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 On Mon, 23 May 2011 14:19:00 +0300, "Michael S. Tsirkin" wrote: > I do understand how it seems a waste to leave direct space > in the ring while we might in practice have space > due to indirect. Didn't come up with a nice way to > solve this yet - but 'no worse than now :)' Let's just make it "bool free_old_xmit_skbs(unsigned int max)". max == 2 for the normal xmit path, so we're low latency but we keep ahead on average. max == -1 for the "we're out of capacity, we may have to stop the queue". That keeps it simple and probably the right thing... Thanks, Rusty. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCHv2 10/14] virtio_net: limit xmit polling Date: Wed, 25 May 2011 11:05:04 +0930 Message-ID: <8739k3k1fb.fsf@rustcorp.com.au> References: <877h9kvlps.fsf@rustcorp.com.au> <20110522121008.GA12155@redhat.com> <87boyutbjg.fsf@rustcorp.com.au> <20110523111900.GB27212@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Krishna Kumar , Carsten Otte , lguest-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Shirley Ma , kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, habanero-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, Heiko Carstens , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, steved-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org, Christian Borntraeger , Tom Lendacky , Martin Schwidefsky , linux390-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20110523111900.GB27212-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lguest-bounces+glkvl-lguest=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: lguest-bounces+glkvl-lguest=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org List-Id: netdev.vger.kernel.org On Mon, 23 May 2011 14:19:00 +0300, "Michael S. Tsirkin" wrote: > I do understand how it seems a waste to leave direct space > in the ring while we might in practice have space > due to indirect. Didn't come up with a nice way to > solve this yet - but 'no worse than now :)' Let's just make it "bool free_old_xmit_skbs(unsigned int max)". max == 2 for the normal xmit path, so we're low latency but we keep ahead on average. max == -1 for the "we're out of capacity, we may have to stop the queue". That keeps it simple and probably the right thing... Thanks, Rusty.