From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753681AbaHUEbW (ORCPT ); Thu, 21 Aug 2014 00:31:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53805 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbaHUEbU (ORCPT ); Thu, 21 Aug 2014 00:31:20 -0400 Message-ID: <53F575F8.7000208@redhat.com> Date: Thu, 21 Aug 2014 12:30:48 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" , Jiri Pirko CC: Pankaj Gupta , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, davem@davemloft.net, dgibson@redhat.com, vfalico@gmail.com, edumazet@google.com, vyasevic@redhat.com, hkchu@google.com, wuzhy@linux.vnet.ibm.com, xemul@parallels.com, therbert@google.com, bhutchings@solarflare.com, xii@google.com, stephen@networkplumber.org Subject: Re: [RFC 2/4] tuntap: Publish tuntap maximum number of queues as module_param References: <1408369040-1216-1-git-send-email-pagupta@redhat.com> <1408369040-1216-3-git-send-email-pagupta@redhat.com> <20140820105817.GB1916@nanopsycho.orion> <20140820111724.GE17371@redhat.com> In-Reply-To: <20140820111724.GE17371@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/20/2014 07:17 PM, Michael S. Tsirkin wrote: > On Wed, Aug 20, 2014 at 12:58:17PM +0200, Jiri Pirko wrote: >> > Mon, Aug 18, 2014 at 03:37:18PM CEST, pagupta@redhat.com wrote: >>> > > This patch publishes maximum number of tun/tap queues allocated as a >>> > > read_only module parameter which a user space application like libvirt >>> > > can make use of to limit maximum number of queues. Value of read_only >>> > > module parameter can be writable only at module load time. If no value is set >>> > > at module load time a default value 256 is used which is equal to maximum number >>> > > of vCPUS allowed by KVM. >>> > > >>> > > Administrator can specify maximum number of queues only at the driver >>> > > module load time. >>> > > >>> > >Signed-off-by: Pankaj Gupta >>> > >--- >>> > > drivers/net/tun.c | 13 +++++++++++-- >>> > > 1 files changed, 11 insertions(+), 2 deletions(-) >>> > > >>> > >diff --git a/drivers/net/tun.c b/drivers/net/tun.c >>> > >index acaaf67..1f518e2 100644 >>> > >--- a/drivers/net/tun.c >>> > >+++ b/drivers/net/tun.c >>> > >@@ -119,6 +119,9 @@ struct tap_filter { >>> > > >>> > > #define TUN_FLOW_EXPIRE (3 * HZ) >>> > > >>> > >+static int max_tap_queues = MAX_TAP_QUEUES; >>> > >+module_param(max_tap_queues, int, S_IRUGO); >> > >> > Please do not introduce new module paramaters. Please other ways to >> > interchange values with userspace. > I suggested this initially, but thinking more about it, I agree. > > It's a global limit (necessary to limit memory utilization by > userspace), but it should be possible to change it > after module load. How about pass this limit through ifr during TUNSETIFF, then alloc_netdev_mq() can use this limit.