From mboxrd@z Thu Jan 1 00:00:00 1970 From: James King Subject: Re: debugging kernel during packet drops Date: Tue, 23 Mar 2010 10:04:22 -0700 Message-ID: <38bcb3ec1003231004y7672ad38v2c16f8c7d042f586@mail.gmail.com> References: <4BA74950.6000305@infopact.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: netfilter-devel@vger.kernel.org To: Jorrit Kronjee Return-path: Received: from mail-vw0-f46.google.com ([209.85.212.46]:55242 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752921Ab0CWREX (ORCPT ); Tue, 23 Mar 2010 13:04:23 -0400 Received: by vws6 with SMTP id 6so944404vws.19 for ; Tue, 23 Mar 2010 10:04:23 -0700 (PDT) In-Reply-To: <4BA74950.6000305@infopact.nl> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Mon, Mar 22, 2010 at 3:41 AM, Jorrit Kronjee wrote: > At around 300 kpps, the amount of packet drops is 40 kpps. For me, this > amount is too significant to ignore. I see the load average go from a > comfortable 0.00 to 1.78, mainly caused by ksoftirqd processes. At 200 > kpps, the average amount of packet drops is 23 kpps. At 100 kpps, it's > still 2 kpps. > > When I disable the hashlimit module the packet drops disappear again. > Now I know that hashlimit is made for more than one thing, namely > limiting packets based on source/destination host and source/destination > port, so it's not as efficient as it could be for my purposes. I could > rewrite it, but before I do that, I would like to know if the module > itself is really what's causing it, or if there's some underlying cause > that I'm not seeing. So my question in short: how can I discover why > it's dropping packets? I'm not sure whether it's even related to the problem you're having, but I had a similar problem on a bnx2 interface with high packet rates when using l7-filter. ifconfig reported huge numbers of dropped packets, corresponding to rx_fw_discards from "ethtool -S ethX" output. I resolved this by bumping up the driver RX ring size (which was defaulting to 100 out of a maximum possible size of 1020).