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[91.114.219.213]) by smtp.gmail.com with ESMTPSA id ck17-20020a5d5e91000000b002383e977920sm5277920wrb.110.2022.11.06.11.11.01 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 06 Nov 2022 11:11:01 -0800 (PST) Message-ID: <49fb01fa-abda-46eb-cf47-31d48810d7eb@gmail.com> Date: Sun, 6 Nov 2022 20:11:00 +0100 Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Content-Language: en-US To: xenomai@lists.linux.dev From: Robert Berger Subject: cyclictest vs. latmus Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, I run some test cases with cyclictest and cyclictest built for xenomai 3 for a couple of years now and want to switch to xenomai 4/evl. Looks like I managed to compile an evl kernel and the evllib and I use latmus instead of cyclictest (not sure if I'm doing that correctly) and also I compare the results against cyclictest (not sure it's right to do that they way I'm doing it). Anyways, sorry for the lengthy document I came of with[1] with histograms and questions. Here are my questions, which you can find in a nicer formatted way in the doc[1]. = evl Kernel - CONFIG_PREEMPT_NONE - cyclictest = My understanding is, that evl works similar to xenomai 3, meaning that you need to compile/link an application against libevl for evl to kick in. I would expect figures 15 and 16 on page 10 to look like figures 3 and 4 on page 4. What’s odd is *) the outlier in the graph without load is bigger than the one with load (1.3 ms vs. 550 us), which should be the opposite *) the outlier in the graph with load should be like the one in figure 4 which is around 10 ms, but it is more like 550 us - please note that the kernel config contains CONFIG_PREEMPT_NONE=y and CONFIG_EVL=y Does this observation imply, that an evl kernel modifies the behavior of the "vanilla" Linux scheduler for processes which should run on the "standard/vanilla" Linux scheduler? = evl Kernel - CONFIG_EVL - latmus = I am not quite sure if/how latmus compares to cyclictest. Ideally I would like to compare histograms produced by latmus against those I produce with cyclictest. Let’s have a look at graphs 17 and 18 on page 11. *) the outlier in the graph without load is bigger than the one with load (780 us vs. 700 us), which should be the opposite *) xenomai 3 with cyclictest compiled for xenomai - figures 13 and 14 on page 9 performs significantly better than evl with latmus **) no load outlier: xenomai 3(cyclictest): 26 us - evl(latmus): 780 us **) load outlier: xenomai 3(cyclictest): 65 us - evl(latmus): 700 us *) a preempt-rt patched kernel with cyclictest - figures 9 and 10 on page 7 performs significantly better than evl with latmus **) no load outlier: preempt-rt(cyclictest): 120 us - evl(latmus): 780 us **) load outlier: preempt-rt(cyclictest): 119 us - evl(latmus): 700 us *) a vanilla kernel with CONFIG_PREEMPT with cyclictest - figures 7 and 8 on page 6 performs similar to evl with latmus **) no load outlier: preempt-rt(cyclictest): 880 us - evl(latmus): 780 us **) load outlier: preempt-rt(cyclictest): 720 us - evl(latmus): 700 us Please check the .pdf here[1] for more details: [1] https://drive.google.com/drive/folders/1_5PZ_4sQxvL5MbiQU1Y1kUXC5IjF5SSX?usp=sharing Regards, Robert -- Robert Berger Embedded Software Evangelist Reliable Embedded Systems Consulting Training Engineering URL: https://www.reliableembeddedsystems.com Schedule a web meeting: https://calendly.com/reliableembeddedsystems/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --