Re: Changing the default scheduler
On Tue, May 24, 2016 at 7:59 AM, Renato Utsch wrote: > The idea is to patch the kernel. I am trying to discover how I can set the > default scheduler for new processes, so that I can test the behavior of any > schedulers that I may write. Do you have any ideas? > > Em Seg, 23 de mai de 2016 10:05 AM, Mulyadi Santosa < > mulyadi.sant...@gmail.com> escreveu: > >> On Fri, May 20, 2016 at 6:51 AM, Renato Utsch >> wrote: >> >>> Hello, >>> >>> I am a new developer trying to learn how to tinker with the kernel. I >>> searched on the internet but couldn't find much info about this (and >>> couldn't find any info up to date). >>> >>> My question is, how does the kernel decide which is the default >>> scheduler that all processes start with? I can change the scheduler of a >>> process by sched_setscheduler(), but how do I change *all* processes from >>> using the CFS scheduler to, for example, the RR scheduler? >>> >>> Sorry if this is too basic, but I don't know where to search for this. >>> If you guys could point me places where I can learn more about this, I >>> would be grateful. >>> >>> ___ >>> Kernelnewbies mailing list >>> Kernelnewbies@kernelnewbies.org >>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >>> >>> >> Hi.. >> >> putting aside scheduler plugins module that once exist and maintained >> (not sure now), I guess the only way to switch to new scheduler is to patch >> your kernel first (if you haven't do that) with scheduler patch such as Con >> Kolivas BFS and reboot to that new kernel. >> >> >> -- >> regards, >> >> Mulyadi Santosa >> Freelance Linux trainer and consultant >> >> blog: the-hydra.blogspot.com >> training: mulyaditraining.blogspot.com >> > Hi... Probably you need to provide several kernel image, each contains different scheduler algorithm you want to test. So in other word, IMHO, the only way to test different scheduler algorithm is to boot to different kernel each time. CMIIW -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Request for guidance
Hi Abhishek, There are some open source project where you can contribute too but I would suggest first you to work on Kernel Bugs available at https://bugzilla.kernel.org. This would boost your confidence. Regards Sanjeev Sharma On Tue, May 24, 2016 at 7:06 AM, Abhishek wrote: > Hi All, > > I am an Embedded Software Engineer with 3+ years of experience. I am > fascinated by kernel development and want to be a device driver developer. > > I have done following so far. > #Studied LDD3. > #Subscribed to eudyptula challenge and submitted solution > for 4th task(waiting for next task). > #Have compiled and installed kernel successfully on multiple boards. > > I want to start contributing to kernel so I looked into staging and > found that I can not work on TODO unless I have required hardware to > test patch (which unfortunately I don't have). > > Requesting you to guide me about how to start working on kernel/device > drivers development. > > Thanks, > Abhishek > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Request for guidance
Hi All, I am an Embedded Software Engineer with 3+ years of experience. I am fascinated by kernel development and want to be a device driver developer. I have done following so far. #Studied LDD3. #Subscribed to eudyptula challenge and submitted solution for 4th task(waiting for next task). #Have compiled and installed kernel successfully on multiple boards. I want to start contributing to kernel so I looked into staging and found that I can not work on TODO unless I have required hardware to test patch (which unfortunately I don't have). Requesting you to guide me about how to start working on kernel/device drivers development. Thanks, Abhishek ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Changing the default scheduler
The idea is to patch the kernel. I am trying to discover how I can set the default scheduler for new processes, so that I can test the behavior of any schedulers that I may write. Do you have any ideas? Em Seg, 23 de mai de 2016 10:05 AM, Mulyadi Santosa < mulyadi.sant...@gmail.com> escreveu: > On Fri, May 20, 2016 at 6:51 AM, Renato Utsch > wrote: > >> Hello, >> >> I am a new developer trying to learn how to tinker with the kernel. I >> searched on the internet but couldn't find much info about this (and >> couldn't find any info up to date). >> >> My question is, how does the kernel decide which is the default scheduler >> that all processes start with? I can change the scheduler of a process by >> sched_setscheduler(), but how do I change *all* processes from using the >> CFS scheduler to, for example, the RR scheduler? >> >> Sorry if this is too basic, but I don't know where to search for this. If >> you guys could point me places where I can learn more about this, I would >> be grateful. >> >> ___ >> Kernelnewbies mailing list >> Kernelnewbies@kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> > Hi.. > > putting aside scheduler plugins module that once exist and maintained (not > sure now), I guess the only way to switch to new scheduler is to patch your > kernel first (if you haven't do that) with scheduler patch such as Con > Kolivas BFS and reboot to that new kernel. > > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: is there any actual usage of the device tree node "/chosen@0"?
On Mon, May 23, 2016 at 01:51:36PM -0400, Robert P. J. Day wrote: > so there are apparently three files that *check* for that alternate > name, but not a single .dts or .dtsi that actually uses it. is there > any value to that alternate name? Why are you asking that here and not on the device tree mailing list? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
is there any actual usage of the device tree node "/chosen@0"?
currently perusing the kernel code for device tree processing and stumbled across this in drivers/of/base.c: void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align)) { struct property *pp; of_aliases = of_find_node_by_path("/aliases"); of_chosen = of_find_node_by_path("/chosen"); if (of_chosen == NULL) of_chosen = of_find_node_by_path("/chosen@0"); ? if (of_chosen) { ... snip ... that pretty clearly says that "/chosen@0" is an equivalent node name for "/chosen", correct? but why was that equivalence first defined? if i scan the entire kernel source tree, this is all i get: $ grep -r "/chosen@0" * arch/powerpc/boot/oflib.c: chosen = of_finddevice("/chosen@0"); drivers/of/base.c: of_chosen = of_find_node_by_path("/chosen@0"); drivers/of/fdt.c: offset = fdt_path_offset(fdt, "/chosen@0"); $ so there are apparently three files that *check* for that alternate name, but not a single .dts or .dtsi that actually uses it. is there any value to that alternate name? rday -- Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Finding GPIO names under Linux
On Mon, May 23, 2016 at 04:05:23PM +0200, Johannes Thoma wrote: > Dear list, > > I am writing a driver which uses the "new" descriptor interface of the > GPIO library. As far as I have understood it, gpiod_get(8) is the way to > allocate (and also lock?) GPIOs pins for use. My question is how do I > find what to pass as the con_id parameter (this should identify the pin > but please correct me if I am wrong, in that case how to I tell > gpiod_get which pin I want?). Is there a file somewhere where I can find > the pin names of my hardware (which is a raspberry 1 for now), something > like /sys/class/gpio/xxx/gpio_pin_names or so, or do I have to look them > up in the device tree or somewhere else? Or do I have to > configure the pin somewhere in the device tree? What I would like to > do is offer an interface (via configfs) where the pins the sensor is > attached can be configured dynamically at run-time. > > The driver itself is OpenSource (GPL) and can be obtained at > > http://github.com/johannesthoma/linux-hc-sro4 > > (iio branch is currently the dev branch where this problem occurs). > > Thanks a lot, A while ago i was trying to understand how to use descriptor based interface playing with my RPi, you can find ressults here: https://github.com/krinkinmu/rpi-gpio-example (*.tex files are in russian, sorry), IFAIU, you have to specify name in device tree before you can use it. > > - Johannes > > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Finding GPIO names under Linux
Dear list, I am writing a driver which uses the "new" descriptor interface of the GPIO library. As far as I have understood it, gpiod_get(8) is the way to allocate (and also lock?) GPIOs pins for use. My question is how do I find what to pass as the con_id parameter (this should identify the pin but please correct me if I am wrong, in that case how to I tell gpiod_get which pin I want?). Is there a file somewhere where I can find the pin names of my hardware (which is a raspberry 1 for now), something like /sys/class/gpio/xxx/gpio_pin_names or so, or do I have to look them up in the device tree or somewhere else? Or do I have to configure the pin somewhere in the device tree? What I would like to do is offer an interface (via configfs) where the pins the sensor is attached can be configured dynamically at run-time. The driver itself is OpenSource (GPL) and can be obtained at http://github.com/johannesthoma/linux-hc-sro4 (iio branch is currently the dev branch where this problem occurs). Thanks a lot, - Johannes ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Changing the default scheduler
On Fri, May 20, 2016 at 6:51 AM, Renato Utsch wrote: > Hello, > > I am a new developer trying to learn how to tinker with the kernel. I > searched on the internet but couldn't find much info about this (and > couldn't find any info up to date). > > My question is, how does the kernel decide which is the default scheduler > that all processes start with? I can change the scheduler of a process by > sched_setscheduler(), but how do I change *all* processes from using the > CFS scheduler to, for example, the RR scheduler? > > Sorry if this is too basic, but I don't know where to search for this. If > you guys could point me places where I can learn more about this, I would > be grateful. > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > Hi.. putting aside scheduler plugins module that once exist and maintained (not sure now), I guess the only way to switch to new scheduler is to patch your kernel first (if you haven't do that) with scheduler patch such as Con Kolivas BFS and reboot to that new kernel. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies