Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762051AbYJJQxo (ORCPT ); Fri, 10 Oct 2008 12:53:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756585AbYJJQxc (ORCPT ); Fri, 10 Oct 2008 12:53:32 -0400 Received: from wr-out-0506.google.com ([64.233.184.225]:13421 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757864AbYJJQxb (ORCPT ); Fri, 10 Oct 2008 12:53:31 -0400 Message-ID: Date: Fri, 10 Oct 2008 17:53:29 +0100 From: "Alex Bennee" To: linux-kernel@vger.kernel.org Subject: rtl8169_get_stats seems to be adding random crap to rx_missed_errors count In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: X-Google-Sender-Auth: dbccc743b9eff407 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3547 Lines: 89 Hi, I've been seeing odd behaviour in the ifconfig output for my rtl8169 based network device. The ifconfig output had a very high number of dropped packets in the display which changed massively every time I checked. I tracked it down to /proc/net/dev and the a few test patches it seems the rc_missed field is the culprit. I did a test patch of the form: +++ b/drivers/net/r8169.c @@ -3062,10 +3062,16 @@ static struct net_device_stats *rtl8169_get_stats(struct net_device *dev) unsigned long flags; if (netif_running(dev)) { + u32 missed; spin_lock_irqsave(&tp->lock, flags); - dev->stats.rx_missed_errors += RTL_R32(RxMissed); + missed = RTL_R32(RxMissed); RTL_W32(RxMissed, 0); spin_unlock_irqrestore(&tp->lock, flags); + + dev->stats.rx_missed_errors += missed; + if (missed) + printk(KERN_INFO "rtl8169_get_stats added %d to missed count\n", missed); + } return &dev->stats; And low and behold I see this behaviour: [ 946.160188] rtl8169_get_stats added 250834943 to missed count [ 946.160354] rtl8169_get_stats added 20768 to missed count [ 946.160411] rtl8169_get_stats added 7032 to missed count [ 946.160425] rtl8169_get_stats added 1677 to missed count [ 946.160439] rtl8169_get_stats added 1577 to missed count [ 946.160452] rtl8169_get_stats added 1543 to missed count [ 946.160465] rtl8169_get_stats added 1517 to missed count [ 946.160479] rtl8169_get_stats added 1572 to missed count [ 946.160492] rtl8169_get_stats added 1586 to missed count [ 946.160504] rtl8169_get_stats added 1284 to missed count [ 948.164206] rtl8169_get_stats added 250864594 to missed count [ 948.164374] rtl8169_get_stats added 21004 to missed count [ 948.164434] rtl8169_get_stats added 7385 to missed count [ 948.164447] rtl8169_get_stats added 1631 to missed count [ 948.164461] rtl8169_get_stats added 1574 to missed count [ 948.164475] rtl8169_get_stats added 1645 to missed count [ 948.164489] rtl8169_get_stats added 1583 to missed count [ 948.164503] rtl8169_get_stats added 1561 to missed count [ 948.164523] rtl8169_get_stats added 2314 to missed count [ 948.164534] rtl8169_get_stats added 1300 to missed count [ 950.168182] rtl8169_get_stats added 250857857 to missed count [ 950.168345] rtl8169_get_stats added 20465 to missed count [ 950.168401] rtl8169_get_stats added 6903 to missed count [ 950.168416] rtl8169_get_stats added 1711 to missed count [ 950.168430] rtl8169_get_stats added 1585 to missed count [ 950.168443] rtl8169_get_stats added 1532 to missed count [ 950.168456] rtl8169_get_stats added 1520 to missed count [ 950.168469] rtl8169_get_stats added 1539 to missed count [ 950.168483] rtl8169_get_stats added 1588 to missed count [ 950.168494] rtl8169_get_stats added 1282 to missed count It looks very much like the number being read is a decreasing counter rather than anything else. Has anyone got a copy of the data sheet and can confirm that: RxMissed = 0x4c, is the correct offset for the register and it doesn't need any special handling to be read? -- Alex, homepage: http://www.bennee.com/~alex/ -- Alex, homepage: http://www.bennee.com/~alex/ -- 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/