From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hagen Paul Pfeifer Subject: Re: [PATCH 1/2] udp: add tracepoints for queueing skb to rcvbuf Date: Tue, 21 Jun 2011 16:48:39 +0200 Message-ID: <5b828bb3667480edda9a4a77918007ee@localhost> References: <65795E11DBF1E645A09CEC7EAEE94B9C402B96E4@USINDEVS02.corp.hds.com> <65795E11DBF1E645A09CEC7EAEE94B9C402B96E5@USINDEVS02.corp.hds.com> <20110621104742.GA16311@hmsreliant.think-freely.org> <4123e3d3ce0192e63947178f249d3411@localhost> <20110621135009.GD16311@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Satoru Moriya , , Seiji Aguchi , Steven Rostedt To: Neil Horman Return-path: Received: from alternativer.internetendpunkt.de ([88.198.24.89]:49624 "EHLO geheimer.internetendpunkt.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752281Ab1FUOsk (ORCPT ); Tue, 21 Jun 2011 10:48:40 -0400 In-Reply-To: <20110621135009.GD16311@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 21 Jun 2011 09:50:09 -0400, Neil Horman wrote: > I hadn't really thought about that much, but yes, I suppose I could migrate > dropwatch to export kfree_skb data via perf. Admittedly I don't know much > about > the perf api. Do you have any pointers on its use (to save me time in > figuring > out how it all works)? If so I'll start looking into it. http://git.kernel.org/?p=status/powertop/powertop.git;a=tree;f=perf;hb=HEAD is probably a good starting point. Especially perf_bundle.cpp:handle_trace_point(). But I am not sure if this is the most clever way. The direct us of the perf api is somewhat dodgy (not sure if the ABI will change). IIRC Steven Rostedt wrote about a user space library (I CC'ed Steven). BUT: tracing via /sys/kernel/debug/tracing/* may be enough, eventually there is no need for perf at all. Then trace-cmd may provide some nice ideas how to wrap the /sys/kernel/debug/tracing interface programmatically. The idea behind dropwatch is great! There is currently to much unconsolidated information. It takes a genius to understand where and later why packets are dropped. A userspace tool where no kernel patch is required is a big plus! ;-) Hagen