From owner-freebsd-arm@FreeBSD.ORG Tue Sep 9 15:02:39 2008 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 18E20106564A; Tue, 9 Sep 2008 15:02:39 +0000 (UTC) (envelope-from sam@freebsd.org) Received: from ebb.errno.com (ebb.errno.com [69.12.149.25]) by mx1.freebsd.org (Postfix) with ESMTP id C0B2D8FC22; Tue, 9 Sep 2008 15:02:38 +0000 (UTC) (envelope-from sam@freebsd.org) Received: from trouble.errno.com (trouble.errno.com [10.0.0.248]) (authenticated bits=0) by ebb.errno.com (8.13.6/8.12.6) with ESMTP id m89F2aGP054541 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 9 Sep 2008 08:02:38 -0700 (PDT) (envelope-from sam@freebsd.org) Message-ID: <48C6900C.8070708@freebsd.org> Date: Tue, 09 Sep 2008 08:02:36 -0700 From: Sam Leffler Organization: FreeBSD Project User-Agent: Thunderbird 2.0.0.9 (X11/20071125) MIME-Version: 1.0 To: Jacques Fourie References: <20080909175556.07bac5f0.stas@FreeBSD.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-DCC--Metrics: ebb.errno.com; whitelist Cc: freebsd-arm@freebsd.org Subject: Re: Routing benchmarks X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Sep 2008 15:02:39 -0000 Jacques Fourie wrote: > On Tue, Sep 9, 2008 at 3:55 PM, Stanislav Sedov wrote: > >> On Tue, 9 Sep 2008 15:33:30 +0200 >> "Jacques Fourie" mentioned: >> >> >>> Hi, >>> >>> I've performed some benchmark tests on my Gumstix Connex 400 (Intel >>> Xscale PXA 255 CPU clocked at 400MHz) with a netDuo expansion board. >>> This board has two smc network interfaces. I configure the gumstix as >>> a router and measure network throughput with netperf running on >>> seperate boxes on either side of the gumstix. My initial tests showed >>> a TCP throughput of 2Mbit/s. After adapting the smc driver to use DMA >>> this figure went up to 7Mbit/s. Although this is a significant >>> improvement, it still seems to be a bit slow. Does anyone have any >>> tips on how I can go about to try and figure out where the bottleneck >>> lies? Initial profiling showed that a significant amount of time was >>> spent doing memory to memory copies of data, but after the DMA change >>> profiling does not show any obvious culprits. >>> >>> >> Have you tried checking the speed of the interface itself? Without >> routing involved? May it be the interfaces itself being so slow? >> >> -- >> Stanislav Sedov >> ST4096-RIPE >> >> > > Running netserver on the gumstix shows a throughput of 2.4Mbit/s. At > the moment I can't get if_bridge to work - will try to figure out what > is going on. A bridging benchmark may be more informative. > You said you did profiling but you didn't provide the data to inspect. It's possible kernel profiling has never been tried on your platform; did you sanity check the results? (e.g. run a known test load and check results; verify all routines that should execute appear in the profile). Also if copy overhead shows up as significant look to see why those copies are being done; it's often possible to avoid a copy. My experience in working with architectures like this is that cache handling can be a significant cost that doesn't always show up on a profile. Also you may find useful information by tracking mbufs using the h/w clock at important places along the "fast path" then look at whether the overhead for each step is reasonable. I did this for bridged traffic by forcing the rx dma to go to an mbuf+cluster then used the free storage in the mbuf header to store timestamps. At the end of the processing path I sorted the data into buckets by the sample points and added a sysctl to dump the histogram to see min/max/avg. Sam