* [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? @ 2018-08-08 10:44 Ho Tam 2018-08-08 11:12 ` Greg Gallagher 0 siblings, 1 reply; 7+ messages in thread From: Ho Tam @ 2018-08-08 10:44 UTC (permalink / raw) To: xenomai Hello all, I make a simple code to measure process time on Raspberry pi 0,1,2,3 like: * previous = rt_timer_read();* * for (i=0; i<500; ++i)* * {* * bcm2835_gpio_write(TEST_PIN, HIGH);* * bcm2835_gpio_write(TEST_PIN, LOW);* * }* * now = rt_timer_read();* * process_time = (long) (now - previous);* * if (process_time>worst_time)* * worst_time=process_time;* And I result after several hours running: rpi process_time (us) worst_time (us) 0,1 ~100 115 2,3 ~90 373 It is clear that process time on rpi2,3 is shorter than that on rpi0,1 due to higher speed CPU. However, I don't understand why worst case on rpi2,3 is much larger than that on rpi0,1. I have repeated this test on both xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) and with different task priority, the result is quite consistent. Does anyone have explanation and solution? Thanks and regards, ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-08 10:44 [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? Ho Tam @ 2018-08-08 11:12 ` Greg Gallagher 2018-08-08 15:41 ` Ho Tam 0 siblings, 1 reply; 7+ messages in thread From: Greg Gallagher @ 2018-08-08 11:12 UTC (permalink / raw) To: Ho Tam, xenomai How are you setting up the gpio read and write? Is it possible to post a code snippet for the read and write? Greg Original Message From: mophong@gmail.com Sent: August 8, 2018 6:45 AM To: xenomai@xenomai.org Reply-to: mophong@gmail.com Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? Hello all, I make a simple code to measure process time on Raspberry pi 0,1,2,3 like: * previous = rt_timer_read();* * for (i=0; i<500; ++i)* * {* * bcm2835_gpio_write(TEST_PIN, HIGH);* * bcm2835_gpio_write(TEST_PIN, LOW);* * }* * now = rt_timer_read();* * process_time = (long) (now - previous);* * if (process_time>worst_time)* * worst_time=process_time;* And I result after several hours running: rpi process_time (us) worst_time (us) 0,1 ~100 115 2,3 ~90 373 It is clear that process time on rpi2,3 is shorter than that on rpi0,1 due to higher speed CPU. However, I don't understand why worst case on rpi2,3 is much larger than that on rpi0,1. I have repeated this test on both xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) and with different task priority, the result is quite consistent. Does anyone have explanation and solution? Thanks and regards, _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-08 11:12 ` Greg Gallagher @ 2018-08-08 15:41 ` Ho Tam 2018-08-08 15:52 ` greg gallagher 0 siblings, 1 reply; 7+ messages in thread From: Ho Tam @ 2018-08-08 15:41 UTC (permalink / raw) To: greg; +Cc: xenomai I used bcm2835 library for test, that library is implemented using memory map (mmap). You may check its copied code here: https://github.com/smart-facility/bcm2835/tree/master/src The function I used bcm2835_gpio_write: void bcm2835_gpio_write(uint8_t pin, uint8_t on) { if (on) bcm2835_gpio_set(pin); else bcm2835_gpio_clr(pin); } I have also tested by direct using of bcm2835_gpio_set and bcm2835_gpio_clr fucntions, but result was same as previous test: for (i=0; i<500; ++i) { bcm2835_gpio_set(TEST_PIN); bcm2835_gpio_clr(TEST_PIN); } Since functions in bcm2835 library usually call many other functions, I have also implemented my own gpio library which directly read/write value to GPSET and GPCLR: for (i=0; i<3000; ++i) { *(rpi_gpio_mem_base+7) =(1<<TEST_PIN); //rpi_gpio_mem_base+7 ~ GPSET0 *(rpi_gpio_mem_base+10) =(1<<TEST_PIN); //rpi_gpio_mem_base+10 ~ GPCLR0 } Here rpi_gpio_mem_base has been initialized with mmap before. In this case, both process time and worst time reduce (for sure). But again, worst time on rpi2,3 is larger than 350% process time, while for rpi0,1 worst time ~ 120% process time. Regards, On Wed, Aug 8, 2018 at 8:12 PM Greg Gallagher <greg@embeddedgreg.com> wrote: > > How are you setting up the gpio read and write? Is it possible to post a > code snippet for the read and write? > > Greg > > Original Message > From: mophong@gmail.com > Sent: August 8, 2018 6:45 AM > To: xenomai@xenomai.org > Reply-to: mophong@gmail.com > Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is > interrupted? > > Hello all, > I make a simple code to measure process time on Raspberry pi 0,1,2,3 like: > > * previous = rt_timer_read();* > * for (i=0; i<500; ++i)* > * {* > * bcm2835_gpio_write(TEST_PIN, HIGH);* > * bcm2835_gpio_write(TEST_PIN, LOW);* > * }* > * now = rt_timer_read();* > * process_time = (long) (now - previous);* > * if (process_time>worst_time)* > * worst_time=process_time;* > > And I result after several hours running: > rpi process_time (us) worst_time (us) > 0,1 ~100 115 > 2,3 ~90 373 > > It is clear that process time on rpi2,3 is shorter than that on rpi0,1 due > to higher speed CPU. However, I don't understand why worst case on rpi2,3 > is much larger than that on rpi0,1. I have repeated this test on both > xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) and with > different task priority, the result is quite consistent. > Does anyone have explanation and solution? > Thanks and regards, > _______________________________________________ > Xenomai mailing list > Xenomai@xenomai.org > https://xenomai.org/mailman/listinfo/xenomai > -- http://www.mophong.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-08 15:41 ` Ho Tam @ 2018-08-08 15:52 ` greg gallagher 2018-08-09 5:48 ` Ho Tam 0 siblings, 1 reply; 7+ messages in thread From: greg gallagher @ 2018-08-08 15:52 UTC (permalink / raw) To: mophong; +Cc: xenomai If you use these functions your test will run in secondary mode. You need to install the rtdm bcm2835_gpio driver for your test to stay in the primary domain. Your tests at the moment are running as normal linux applications even though you have built them with the Xenomai libraries. You'll need enable the gpio module in the kernel build. You should see the gpio pins under /dev/rtdm once the module is loaded. It might be worth while posting your steps for building the application so you can ensure you are indeed building the application to correctly interface with Xenomai. -Greg On 2018-08-08 11:41 AM, Ho Tam wrote: > I used bcm2835 library for test, that library is implemented using > memory map (mmap). You may check its copied code here: > https://github.com/smart-facility/bcm2835/tree/master/src > The function I used bcm2835_gpio_write: > void bcm2835_gpio_write(uint8_t pin, uint8_t on) > { > if (on) > bcm2835_gpio_set(pin); > else > bcm2835_gpio_clr(pin); > } > > I have also tested by direct using of bcm2835_gpio_set > and bcm2835_gpio_clr fucntions, but result was same as previous test: > for (i=0; i<500; ++i) > { > bcm2835_gpio_set(TEST_PIN); > bcm2835_gpio_clr(TEST_PIN); > } > > Since functions in bcm2835 library usually call many other functions, > I have also implemented my own gpio library which directly read/write > value to GPSET and GPCLR: > for (i=0; i<3000; ++i) > { > *(rpi_gpio_mem_base+7) =(1<<TEST_PIN); //rpi_gpio_mem_base+7 ~ GPSET0 > *(rpi_gpio_mem_base+10) =(1<<TEST_PIN); //rpi_gpio_mem_base+10 ~ GPCLR0 > } > Here rpi_gpio_mem_base has been initialized with mmap before. In this > case, both process time and worst time reduce (for sure). But again, > worst time on rpi2,3 is larger than 350% process time, while for > rpi0,1 worst time ~ 120% process time. > Regards, > > > On Wed, Aug 8, 2018 at 8:12 PM Greg Gallagher <greg@embeddedgreg.com > <mailto:greg@embeddedgreg.com>> wrote: > > > How are you setting up the gpio read and write? Is it possible to > post a code snippet for the read and write? > > Greg > > Original Message > From: mophong@gmail.com <mailto:mophong@gmail.com> > Sent: August 8, 2018 6:45 AM > To: xenomai@xenomai.org <mailto:xenomai@xenomai.org> > Reply-to: mophong@gmail.com <mailto:mophong@gmail.com> > Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task > is interrupted? > > Hello all, > I make a simple code to measure process time on Raspberry pi > 0,1,2,3 like: > > * previous = rt_timer_read();* > * for (i=0; i<500; ++i)* > * {* > * bcm2835_gpio_write(TEST_PIN, HIGH);* > * bcm2835_gpio_write(TEST_PIN, LOW);* > * }* > * now = rt_timer_read();* > * process_time = (long) (now - previous);* > * if (process_time>worst_time)* > * worst_time=process_time;* > > And I result after several hours running: > rpi process_time (us) worst_time (us) > 0,1 ~100 115 > 2,3 ~90 373 > > It is clear that process time on rpi2,3 is shorter than that on > rpi0,1 due > to higher speed CPU. However, I don't understand why worst case on > rpi2,3 > is much larger than that on rpi0,1. I have repeated this test on both > xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) > and with > different task priority, the result is quite consistent. > Does anyone have explanation and solution? > Thanks and regards, > _______________________________________________ > Xenomai mailing list > Xenomai@xenomai.org <mailto:Xenomai@xenomai.org> > https://xenomai.org/mailman/listinfo/xenomai > > > > -- > http://www.mophong.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-08 15:52 ` greg gallagher @ 2018-08-09 5:48 ` Ho Tam 2018-08-09 11:02 ` Ho Tam 2018-08-09 11:16 ` Greg Gallagher 0 siblings, 2 replies; 7+ messages in thread From: Ho Tam @ 2018-08-09 5:48 UTC (permalink / raw) To: greg; +Cc: xenomai Hello Greg, Thanks for your answer. There is still something unclear. So far I have worked with mmap + xenomai task on several platforms like Beaglebone (single core), IMX6Q (quad-core), and as you can see, RPI0,1 (BCM2835), it works just fine. Still, I don't understand why this situation ONLY happens on RPI2,3 (BCM2857). Regards, On Thu, Aug 9, 2018 at 12:52 AM greg gallagher <greg@embeddedgreg.com> wrote: > If you use these functions your test will run in secondary mode. You > need to install the rtdm bcm2835_gpio driver for your test to stay in > the primary domain. Your tests at the moment are running as normal > linux applications even though you have built them with the Xenomai > libraries. You'll need enable the gpio module in the kernel build. You > should see the gpio pins under /dev/rtdm once the module is loaded. It > might be worth while posting your steps for building the application so > you can ensure you are indeed building the application to correctly > interface with Xenomai. > > > -Greg > > > On 2018-08-08 11:41 AM, Ho Tam wrote: > > I used bcm2835 library for test, that library is implemented using > > memory map (mmap). You may check its copied code here: > > https://github.com/smart-facility/bcm2835/tree/master/src > > The function I used bcm2835_gpio_write: > > void bcm2835_gpio_write(uint8_t pin, uint8_t on) > > { > > if (on) > > bcm2835_gpio_set(pin); > > else > > bcm2835_gpio_clr(pin); > > } > > > > I have also tested by direct using of bcm2835_gpio_set > > and bcm2835_gpio_clr fucntions, but result was same as previous test: > > for (i=0; i<500; ++i) > > { > > bcm2835_gpio_set(TEST_PIN); > > bcm2835_gpio_clr(TEST_PIN); > > } > > > > Since functions in bcm2835 library usually call many other functions, > > I have also implemented my own gpio library which directly read/write > > value to GPSET and GPCLR: > > for (i=0; i<3000; ++i) > > { > > *(rpi_gpio_mem_base+7) =(1<<TEST_PIN); //rpi_gpio_mem_base+7 ~ GPSET0 > > *(rpi_gpio_mem_base+10) =(1<<TEST_PIN); //rpi_gpio_mem_base+10 ~ GPCLR0 > > } > > Here rpi_gpio_mem_base has been initialized with mmap before. In this > > case, both process time and worst time reduce (for sure). But again, > > worst time on rpi2,3 is larger than 350% process time, while for > > rpi0,1 worst time ~ 120% process time. > > Regards, > > > > > > On Wed, Aug 8, 2018 at 8:12 PM Greg Gallagher <greg@embeddedgreg.com > > <mailto:greg@embeddedgreg.com>> wrote: > > > > > > How are you setting up the gpio read and write? Is it possible to > > post a code snippet for the read and write? > > > > Greg > > > > Original Message > > From: mophong@gmail.com <mailto:mophong@gmail.com> > > Sent: August 8, 2018 6:45 AM > > To: xenomai@xenomai.org <mailto:xenomai@xenomai.org> > > Reply-to: mophong@gmail.com <mailto:mophong@gmail.com> > > Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task > > is interrupted? > > > > Hello all, > > I make a simple code to measure process time on Raspberry pi > > 0,1,2,3 like: > > > > * previous = rt_timer_read();* > > * for (i=0; i<500; ++i)* > > * {* > > * bcm2835_gpio_write(TEST_PIN, HIGH);* > > * bcm2835_gpio_write(TEST_PIN, LOW);* > > * }* > > * now = rt_timer_read();* > > * process_time = (long) (now - previous);* > > * if (process_time>worst_time)* > > * worst_time=process_time;* > > > > And I result after several hours running: > > rpi process_time (us) worst_time (us) > > 0,1 ~100 115 > > 2,3 ~90 373 > > > > It is clear that process time on rpi2,3 is shorter than that on > > rpi0,1 due > > to higher speed CPU. However, I don't understand why worst case on > > rpi2,3 > > is much larger than that on rpi0,1. I have repeated this test on both > > xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) > > and with > > different task priority, the result is quite consistent. > > Does anyone have explanation and solution? > > Thanks and regards, > > _______________________________________________ > > Xenomai mailing list > > Xenomai@xenomai.org <mailto:Xenomai@xenomai.org> > > https://xenomai.org/mailman/listinfo/xenomai > > > > > > > > -- > > http://www.mophong.com > > -- http://www.mophong.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-09 5:48 ` Ho Tam @ 2018-08-09 11:02 ` Ho Tam 2018-08-09 11:16 ` Greg Gallagher 1 sibling, 0 replies; 7+ messages in thread From: Ho Tam @ 2018-08-09 11:02 UTC (permalink / raw) To: greg; +Cc: xenomai Hello, In order to close this topic, I have found a workaround, I isolated all 4 cores of RPI2,3 (isolcpus=0,1,2,3) and now performance is similar to that on RPI0,1. This may not be accepted by someone but for my application, it is acceptable. Thanks and Regards, On Thu, Aug 9, 2018 at 2:48 PM Ho Tam <mophong@gmail.com> wrote: > Hello Greg, > Thanks for your answer. There is still something unclear. So far I have > worked with mmap + xenomai task on several platforms like Beaglebone > (single core), IMX6Q (quad-core), and as you can see, RPI0,1 (BCM2835), it > works just fine. > Still, I don't understand why this situation ONLY happens on RPI2,3 > (BCM2857). > Regards, > > On Thu, Aug 9, 2018 at 12:52 AM greg gallagher <greg@embeddedgreg.com> > wrote: > >> If you use these functions your test will run in secondary mode. You >> need to install the rtdm bcm2835_gpio driver for your test to stay in >> the primary domain. Your tests at the moment are running as normal >> linux applications even though you have built them with the Xenomai >> libraries. You'll need enable the gpio module in the kernel build. You >> should see the gpio pins under /dev/rtdm once the module is loaded. It >> might be worth while posting your steps for building the application so >> you can ensure you are indeed building the application to correctly >> interface with Xenomai. >> >> >> -Greg >> >> >> On 2018-08-08 11:41 AM, Ho Tam wrote: >> > I used bcm2835 library for test, that library is implemented using >> > memory map (mmap). You may check its copied code here: >> > https://github.com/smart-facility/bcm2835/tree/master/src >> > The function I used bcm2835_gpio_write: >> > void bcm2835_gpio_write(uint8_t pin, uint8_t on) >> > { >> > if (on) >> > bcm2835_gpio_set(pin); >> > else >> > bcm2835_gpio_clr(pin); >> > } >> > >> > I have also tested by direct using of bcm2835_gpio_set >> > and bcm2835_gpio_clr fucntions, but result was same as previous test: >> > for (i=0; i<500; ++i) >> > { >> > bcm2835_gpio_set(TEST_PIN); >> > bcm2835_gpio_clr(TEST_PIN); >> > } >> > >> > Since functions in bcm2835 library usually call many other functions, >> > I have also implemented my own gpio library which directly read/write >> > value to GPSET and GPCLR: >> > for (i=0; i<3000; ++i) >> > { >> > *(rpi_gpio_mem_base+7) =(1<<TEST_PIN); //rpi_gpio_mem_base+7 ~ GPSET0 >> > *(rpi_gpio_mem_base+10) =(1<<TEST_PIN); //rpi_gpio_mem_base+10 ~ GPCLR0 >> > } >> > Here rpi_gpio_mem_base has been initialized with mmap before. In this >> > case, both process time and worst time reduce (for sure). But again, >> > worst time on rpi2,3 is larger than 350% process time, while for >> > rpi0,1 worst time ~ 120% process time. >> > Regards, >> > >> > >> > On Wed, Aug 8, 2018 at 8:12 PM Greg Gallagher <greg@embeddedgreg.com >> > <mailto:greg@embeddedgreg.com>> wrote: >> > >> > >> > How are you setting up the gpio read and write? Is it possible to >> > post a code snippet for the read and write? >> > >> > Greg >> > >> > Original Message >> > From: mophong@gmail.com <mailto:mophong@gmail.com> >> > Sent: August 8, 2018 6:45 AM >> > To: xenomai@xenomai.org <mailto:xenomai@xenomai.org> >> > Reply-to: mophong@gmail.com <mailto:mophong@gmail.com> >> > Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task >> > is interrupted? >> > >> > Hello all, >> > I make a simple code to measure process time on Raspberry pi >> > 0,1,2,3 like: >> > >> > * previous = rt_timer_read();* >> > * for (i=0; i<500; ++i)* >> > * {* >> > * bcm2835_gpio_write(TEST_PIN, HIGH);* >> > * bcm2835_gpio_write(TEST_PIN, LOW);* >> > * }* >> > * now = rt_timer_read();* >> > * process_time = (long) (now - previous);* >> > * if (process_time>worst_time)* >> > * worst_time=process_time;* >> > >> > And I result after several hours running: >> > rpi process_time (us) worst_time (us) >> > 0,1 ~100 115 >> > 2,3 ~90 373 >> > >> > It is clear that process time on rpi2,3 is shorter than that on >> > rpi0,1 due >> > to higher speed CPU. However, I don't understand why worst case on >> > rpi2,3 >> > is much larger than that on rpi0,1. I have repeated this test on >> both >> > xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) >> > and with >> > different task priority, the result is quite consistent. >> > Does anyone have explanation and solution? >> > Thanks and regards, >> > _______________________________________________ >> > Xenomai mailing list >> > Xenomai@xenomai.org <mailto:Xenomai@xenomai.org> >> > https://xenomai.org/mailman/listinfo/xenomai >> > >> > >> > >> > -- >> > http://www.mophong.com >> >> > > -- > http://www.mophong.com > -- http://www.mophong.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? 2018-08-09 5:48 ` Ho Tam 2018-08-09 11:02 ` Ho Tam @ 2018-08-09 11:16 ` Greg Gallagher 1 sibling, 0 replies; 7+ messages in thread From: Greg Gallagher @ 2018-08-09 11:16 UTC (permalink / raw) To: Ho Tam; +Cc: xenomai It's possible the domains don't have much to do with your issue. Can you confirm if you are switching modes in the case of the rpi2\3? There isn't anything unique about the rpi2\3 that would impact it only. Are you able to get some info on what the system is doing during the worst case run? This is the only application running at the time? Greg From: mophong@gmail.com Sent: August 9, 2018 1:48 AM To: greg@embeddedgreg.com Reply-to: mophong@gmail.com Cc: xenomai@xenomai.org Subject: Re: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? Hello Greg, Thanks for your answer. There is still something unclear. So far I have worked with mmap + xenomai task on several platforms like Beaglebone (single core), IMX6Q (quad-core), and as you can see, RPI0,1 (BCM2835), it works just fine. Still, I don't understand why this situation ONLY happens on RPI2,3 (BCM2857). Regards, On Thu, Aug 9, 2018 at 12:52 AM greg gallagher <[1]greg@embeddedgreg.com> wrote: If you use these functions your test will run in secondary mode. You need to install the rtdm bcm2835_gpio driver for your test to stay in the primary domain. Your tests at the moment are running as normal linux applications even though you have built them with the Xenomai libraries. You'll need enable the gpio module in the kernel build. You should see the gpio pins under /dev/rtdm once the module is loaded. It might be worth while posting your steps for building the application so you can ensure you are indeed building the application to correctly interface with Xenomai. -Greg On 2018-08-08 11:41 AM, Ho Tam wrote: > I used bcm2835 library for test, that library is implemented using > memory map (mmap). You may check its copied code here: > [2]https://github.com/smart-facility/bcm2835/tree/master/src > The function I used bcm2835_gpio_write: > void bcm2835_gpio_write(uint8_t pin, uint8_t on) > { > if (on) > bcm2835_gpio_set(pin); > else > bcm2835_gpio_clr(pin); > } > > I have also tested by direct using of bcm2835_gpio_set > and bcm2835_gpio_clr fucntions, but result was same as previous test: > for (i=0; i<500; ++i) > { > bcm2835_gpio_set(TEST_PIN); > bcm2835_gpio_clr(TEST_PIN); > } > > Since functions in bcm2835 library usually call many other functions, > I have also implemented my own gpio library which directly read/write > value to GPSET and GPCLR: > for (i=0; i<3000; ++i) > { > *(rpi_gpio_mem_base+7) =(1<<TEST_PIN); //rpi_gpio_mem_base+7 ~ GPSET0 > *(rpi_gpio_mem_base+10) =(1<<TEST_PIN); //rpi_gpio_mem_base+10 ~ GPCLR0 > } > Here rpi_gpio_mem_base has been initialized with mmap before. In this > case, both process time and worst time reduce (for sure). But again, > worst time on rpi2,3 is larger than 350% process time, while for > rpi0,1 worst time ~ 120% process time. > Regards, > > > On Wed, Aug 8, 2018 at 8:12 PM Greg Gallagher <[3]greg@embeddedgreg.com > <mailto:[4]greg@embeddedgreg.com>> wrote: > > > How are you setting up the gpio read and write? Is it possible to > post a code snippet for the read and write? > > Greg > > Original Message > From: [5]mophong@gmail.com <mailto:[6]mophong@gmail.com> > Sent: August 8, 2018 6:45 AM > To: [7]xenomai@xenomai.org <mailto:[8]xenomai@xenomai.org> > Reply-to: [9]mophong@gmail.com <mailto:[10]mophong@gmail.com> > Subject: [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task > is interrupted? > > Hello all, > I make a simple code to measure process time on Raspberry pi > 0,1,2,3 like: > > * previous = rt_timer_read();* > * for (i=0; i<500; ++i)* > * {* > * bcm2835_gpio_write(TEST_PIN, HIGH);* > * bcm2835_gpio_write(TEST_PIN, LOW);* > * }* > * now = rt_timer_read();* > * process_time = (long) (now - previous);* > * if (process_time>worst_time)* > * worst_time=process_time;* > > And I result after several hours running: > rpi process_time (us) worst_time (us) > 0,1 ~100 115 > 2,3 ~90 373 > > It is clear that process time on rpi2,3 is shorter than that on > rpi0,1 due > to higher speed CPU. However, I don't understand why worst case on > rpi2,3 > is much larger than that on rpi0,1. I have repeated this test on both > xenomai 2 and 3, kernel 4.1 and 4.9 (only xenomai 3 in this case) > and with > different task priority, the result is quite consistent. > Does anyone have explanation and solution? > Thanks and regards, > _______________________________________________ > Xenomai mailing list > [11]Xenomai@xenomai.org <mailto:[12]Xenomai@xenomai.org> > [13]https://xenomai.org/mailman/listinfo/xenomai > > > > -- > [14]http://www.mophong.com -- [15]http://www.mophong.com References 1. mailto:greg@embeddedgreg.com 2. https://github.com/smart-facility/bcm2835/tree/master/src 3. mailto:greg@embeddedgreg.com 4. mailto:greg@embeddedgreg.com 5. mailto:mophong@gmail.com 6. mailto:mophong@gmail.com 7. mailto:xenomai@xenomai.org 8. mailto:xenomai@xenomai.org 9. mailto:mophong@gmail.com 10. mailto:mophong@gmail.com 11. mailto:Xenomai@xenomai.org 12. mailto:Xenomai@xenomai.org 13. https://xenomai.org/mailman/listinfo/xenomai 14. http://www.mophong.com/ 15. http://www.mophong.com/ ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-08-09 11:16 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-08-08 10:44 [Xenomai] Xenomai on Raspberry pi 2, 3 - Userspace task is interrupted? Ho Tam 2018-08-08 11:12 ` Greg Gallagher 2018-08-08 15:41 ` Ho Tam 2018-08-08 15:52 ` greg gallagher 2018-08-09 5:48 ` Ho Tam 2018-08-09 11:02 ` Ho Tam 2018-08-09 11:16 ` Greg Gallagher
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