From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <5315ED1F.60602@xenomai.org> Date: Tue, 04 Mar 2014 16:11:27 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <1392993075.52404.YahooMailNeo@web140605.mail.bf1.yahoo.com> <530766CD.3060707@xenomai.org> <1393198348.29895.YahooMailNeo@web140605.mail.bf1.yahoo.com> <530A862C.1060805@xenomai.org> <1393204287.98060.YahooMailNeo@web140606.mail.bf1.yahoo.com> <530B374B.1080507@xenomai.org> <1393298793.43978.YahooMailNeo@web140605.mail.bf1.yahoo.com> <530C6AC6.6030200@xenomai.org> <1393335358.33826.YahooMailNeo@web140603.mail.bf1.yahoo.com> <530C9D87.60805@xenomai.org> <1393871535.96739.YahooMailNeo@web140604.mail.bf1.yahoo.com> <5314CDDA.4030308@xenomai.org> <1393904852.42577.YahooMailNeo@web140603.mail.bf1.yahoo.com> In-Reply-To: <1393904852.42577.YahooMailNeo@web140603.mail.bf1.yahoo.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] User Space Problems List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bruno Tunes de Mello Cc: "xenomai@xenomai.org" On 03/04/2014 04:47 AM, Bruno Tunes de Mello wrote: > Hi Gilles, > > You are right, in the first test, I executed both latency and xeno-test commands. Sorry. > The others test I executed only latency command. > > I tried to enable the discard service on /etc/inetd.conf, I don't know if I did it right, but in /etc/services file I found 'discard 9/tcp sink null' and 'discard 9/udp sink null'. > Then I used the command you said: > xeno-test -l "dohell -s 192.168.0.5 -m /media/linaro/PENDRIVE -l /opt/ltp" -c 0 -p 100 -g histo > > I tested a few times and the better result is: http://pt-br.tinypic.com/r/206mmvn/8 > This result is not so good like that you showed. > > My doubt is if this result is satisfactory (the platform is ready for develop applications) or do you think that I need to do some correction? 70us is a bit high, but on the other hand: - the mx6q is a quad-core, whereas the omap4 is a dual core, the latency increases with the number of cores; - the tests I make on omap4 do not use much of the processor peripherals, such as the graphic co-processor, so, if you use the graphic co-processor, you may observe an increase in latencies as well. Finally, whether this is satisfactory depends on your application. The only way to improve latency is to enable the I-pipe tracer, and try and understand where the maximum latency come from, but this is time consuming. Also, some settings are known to result in an improvement in latencies: - turn off CONFIG_PREEMPT (i.e. enable CONFIG_PREEMPT_NONE), this looks contradictory, as the menu entry says "low latency", but it is talking about Linux latencies, not Xenomai's - build kernel and user-space in thumb2 - disable Xenomai unlocked context switch But do not expect these settings to reduce the latency by more than say 5us. -- Gilles.