From mboxrd@z Thu Jan 1 00:00:00 1970 From: Karsten Desler Subject: Re: _High_ CPU usage while routing (mostly) small UDP packets Date: Tue, 7 Dec 2004 19:38:45 +0100 Message-ID: <20041207183845.GA2078@quickstop.soohrt.org> References: <20041206205305.GA11970@soohrt.org> <20041206134849.498bfc93.davem@davemloft.net> <20041206224107.GA8529@soohrt.org> <41B58A58.8010007@draigBrady.com> <20041207112139.GA3610@soohrt.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: P@draigBrady.com, "David S. Miller" , netdev@oss.sgi.com, linux-kernel@vger.kernel.org Return-path: To: Karsten Desler Content-Disposition: inline In-Reply-To: <20041207112139.GA3610@soohrt.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Karsten Desler wrote: > > Also have a look at http://www.hipac.org/ as netfilter > > has silly scalability properties. > > I did before, but I read on Harald Weltes' weblog that 2.4 gives > slightly worse pps results than 2.6, and since the cpu usage is as high > as it is, I didn't want to take any more performance hits. > I'll try to see what performance impact the netfilter rules have during > peak load. using 2 CPUs System load: 61.4% || Free: 51.0%(0) 26.3%(1) System load: 59.6% || Free: 53.6%(0) 27.3%(1) System load: 59.6% || Free: 53.6%(0) 27.3%(1) System load: 59.7% || Free: 53.6%(0) 27.0%(1) System load: 60.3% || Free: 53.0%(0) 26.4%(1) System load: 51.9% || Free: 60.4%(0) 35.8%(1) <- iptables -F System load: 50.1% || Free: 62.1%(0) 37.7%(1) System load: 50.1% || Free: 62.0%(0) 37.8%(1) System load: 50.6% || Free: 61.6%(0) 37.2%(1) System load: 50.5% || Free: 61.7%(0) 37.3%(1) > > I also notice that a lot of time is spent allocating > > and freeing the packet buffers (and possible hidden > > time due to cache misses due to allocating on one > > CPU and freeing on another?). > > How many [RT]xDescriptors do you have configured by the way? > > 256. I increased them to 1024 shortly after the profiling run, but > didn't notice any change in the cpu usage (will try again with cyclesoak). Again, no effect. Cheers, Karsten