From patchwork Sun Aug 24 20:19:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom Herbert X-Patchwork-Id: 382537 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 86BFD1400D6 for ; Mon, 25 Aug 2014 06:19:54 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753288AbaHXUTu (ORCPT ); Sun, 24 Aug 2014 16:19:50 -0400 Received: from mail-pa0-f73.google.com ([209.85.220.73]:54173 "EHLO mail-pa0-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014AbaHXUTt (ORCPT ); Sun, 24 Aug 2014 16:19:49 -0400 Received: by mail-pa0-f73.google.com with SMTP id kx10so3363432pab.2 for ; Sun, 24 Aug 2014 13:19:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=date:from:to:subject:message-id:user-agent:mime-version :content-type; bh=Z2RhVEfXm0pIw3Mmik9Twh91DWDrVC0vTu1OEO4Sl1U=; b=SbdGZgf+sFuUQZBR/aPbfw5eC9OessDsH0ESfykxeK9OJSyaWBO9ZwFHCkUP8z4Jje pCsDF43SfUKOCjT4IFQ+DLms68ov/KoQskKNEuf9VjqJADgvv7j9AcsJfyJ6FaJxQeAz 2BYa1XQ0VTHeC0Xrm2osOU+bFFj+J2MK6By1qP9YGSlT3clE6w3C4H4LoZSCpZ90Iu8/ FvTaWsIs1hFNGMSQMN1W0uen89YFvIH5XWV7nbCb8AQbII6gqCaxd/nGuK0eoxWdLr+R oPbCgtW+3+Wr4WulXrD8ze2DsBUgS6s641fm3cRDd+/5O9lyIWkfya7t5G7rBPtWBk8C OiZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:subject:message-id:user-agent :mime-version:content-type; bh=Z2RhVEfXm0pIw3Mmik9Twh91DWDrVC0vTu1OEO4Sl1U=; b=eGoCqzK1aw5dbMAbTTTEjbTAtL+WnSHAetmhtFn+tzPu1Hpyv10u0JwEC4jGvtASDX /N/Zo4/d0dxkfPqPOKPSVUt4xlJf5WiEkG5XfrlJjp6gol+8RBCN0mPg+/eIYMeD6LP/ 8W7XXqhAZajoEFHPh3iDX8xh27qy/gWt4+hPDs7yIZENiuJonvxoWwqiW7QY4qS/FvFC viq7W9hbFryncVmd/0+scXC4X5YhhXDsFroFVNXt9WI/9/qDoq/pfwgGmLn+S44ETv3T YlkKl0BMMYc21/KGuTnLoBouJC5Zn9sGgL9OV+nO8xefeRHIMSpCW5Q6GNWaaIOjn0tW kQ4g== X-Gm-Message-State: ALoCoQkkQAbpHBf/y2/J07yEUjBziI2S3/eiBUSJ0ENaCkTxIQtWcq+OsC8h5lchfC3pg2HcMBm4 X-Received: by 10.70.130.135 with SMTP id oe7mr11680131pdb.9.1408911588548; Sun, 24 Aug 2014 13:19:48 -0700 (PDT) Received: from corp2gmr1-2.hot.corp.google.com (corp2gmr1-2.hot.corp.google.com [172.24.189.93]) by gmr-mx.google.com with ESMTPS id t75si1455501yhe.5.2014.08.24.13.19.48 for (version=TLSv1.1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 24 Aug 2014 13:19:48 -0700 (PDT) Received: from tomh.mtv.corp.google.com (tomh.mtv.corp.google.com [172.18.117.126]) by corp2gmr1-2.hot.corp.google.com (Postfix) with ESMTP id 5736E5A42C3; Sun, 24 Aug 2014 13:19:48 -0700 (PDT) Received: by tomh.mtv.corp.google.com (Postfix, from userid 60832) id DC3ED200819; Sun, 24 Aug 2014 13:19:47 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by tomh.mtv.corp.google.com (Postfix) with ESMTP id C42D7200272; Sun, 24 Aug 2014 13:19:47 -0700 (PDT) Date: Sun, 24 Aug 2014 13:19:47 -0700 (PDT) From: Tom Herbert To: davem@davemloft.net, netdev@vger.kernel.org Subject: [PATCH net-next] net: Functions to report space available in device TX queues Message-ID: User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch adds netdev_tx_avail_queue and netdev_avail_queue which are used to report number of bytes available in transmit queues per BQL. The functions call dql_avail which returns BQL limit minus number of inflight bytes. These functions can be called without txlock, for instance to ascertain how much data should be dequeued from a qdisc in a batch. When called without the tx_lock, the result is technically a hint, subsequently when the tx_lock is done for a transmit it is possible the availability has changed (for example a transmit completion may have freed up more space in the queue or changed the limit). Signed-off-by: Tom Herbert --- include/linux/netdevice.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 0fac884..13883c1 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2544,6 +2544,30 @@ static inline void netdev_completed_queue(struct net_device *dev, netdev_tx_completed_queue(netdev_get_tx_queue(dev, 0), pkts, bytes); } +static inline int netdev_tx_avail_queue(struct netdev_queue *dev_queue) +{ +#ifdef CONFIG_BQL + return dql_avail(&dev_queue->dql); +#else + return DQL_MAX_LIMIT; +#endif +} + +/** + * netdev_avail_queue - report how much space is availble for xmit + * @dev: network device + * + * Report the amount of space available in the TX queue in terms of + * number of bytes. This returns the number of bytes avaiable per + * DQL. This function may be called without taking the txlock on + * the device, however in that case the result should be taken as + * a (strong) hint. + */ +static inline int netdev_avail_queue(struct net_device *dev_queue) +{ + return netdev_tx_avail_queue(netdev_get_tx_queue(dev_queue, 0)); +} + static inline void netdev_tx_reset_queue(struct netdev_queue *q) { #ifdef CONFIG_BQL