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Microsecond (or one ms) time resolution on an embedded device (Linux Kernel)


Microsecond (or one ms) time resolution on an embedded device (Linux Kernel)

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Microsecond (or one ms) time resolution on an embedded device (Linux Kernel)
Tag : c , By : user165781
Date : January 02 2021, 06:48 AM


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Linux kernel device driver to DMA into kernel space


Tag : linux , By : Mahesh
Date : March 29 2020, 07:55 AM
wish helps you
kmalloc is indeed one source to get the buffer. Another can be alloc_page with the GFP_DMA flag.

How is the microsecond time of linux gettimeofday() obtained and what is its accuracy?


Tag : linux , By : christiandsg
Date : March 29 2020, 07:55 AM
help you fix your problem How is the microsecond resolution/granularity of gettimeofday() accomplished?
Linux runs on many different hardware platforms, so the specifics differ. On a modern x86 platform Linux uses the Time Stamp Counter, also known as the TSC, which is driven by multiple of a crystal oscillator running at 133.33 MHz. The crystal oscillator provides a reference clock to the processor, and the processor multiplies it by some multiple - for example on a 2.93 GHz processor the multiple is 22. The TSC historically was an unreliable source of time because implementations would stop the counter when the processor went to sleep, or because the multiple wasn't constant as the processor shifted multipliers to change performance states or throttle down when it got hot. Modern x86 processors provide a TSC that is constant, invariant, and non-stop. On these processors the TSC is an excellent high resolution clock and the Linux kernel determines an initial approximate frequency at boot time. The TSC provides microsecond resolution for the gettimeofday() system call and nanosecond resolution for the clock_gettime() system call.

Measuring Time in Linux Kernel Space With Sub-Microsecond Precision


Tag : c , By : nickthecook
Date : March 29 2020, 07:55 AM
this one helps. The ktime_get() function returns ktime_t, which has nanosecond resolution.

What is the minimum amount of RAM required to run Linux kernel on an Embedded device?


Tag : linux-kernel , By : liquidx
Date : March 29 2020, 07:55 AM
wish help you to fix your issue It's possible to shrink it down to ~600 KiB. Check the work done by Tom Zanussi from Intel. Presentation from Tom and Wiki page about the topic.
UPDATE. Tom published interesting statistics about memory use by different subsystems in the kernel. He did research during that time when he was working on the project.

Embedded Linux Kernel and Desktop Linux Kernel Difference


Tag : linux , By : anov
Date : March 29 2020, 07:55 AM
wish helps you yes, there is one official kernel for different architectures at kernel.org
There may be forks with special hardware handling, additional drivers, etc. for specific customers (hardware suppliers like Samsung)
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