From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: Execution time References: From: Jan Kiszka Message-ID: Date: Mon, 8 Mar 2021 11:23:33 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Leandro Bucci , xenomai On 03.03.21 15:45, Leandro Bucci via Xenomai wrote: > Hi, I noticed a very strange but also interesting fact. When a certain > periodic task is executed, if the period is small (for example 0.5ms) I > have that the execution times are more or less constant (about 5 micro > seconds). If, on the other hand, the period of the same task is larger (for > example 10ms), the execution times are less predictable and range from 5 > micro seconds to 15 micro seconds. > > How is this possible? I am using a raspberry Pi3 and the task is running on > a core dedicated to xenomai. In general, you can see cache "temperature" effects when reducing the period of a task: The more frequently it runs, the hotter the cache will be and the less likely it is that relevant content for that task has be evicted. But all that depends on many factors, the non-rt load, the load of the task itself, the caching system etc. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux