On Tue, Jul 17, 2012 at 1:20 AM, Victor Rodriguez <vm.rod25@gmail.com> wrote:
Hi Manavendra
Have you think in a driver that you can call when the context switch happen? If this can be detected (more investigation on this area is required). If that is possible we can create the driver to measure the time according to the interruption.
Thanks a lot and regards
Victor Rodriguez
On Mon, Jul 16, 2012 at 2:28 PM, Manavendra Nath Manav <mnm.kernel@gmail.com> wrote:
How to measure time spent in context switch in Linux i.e. the time the application stays suspended while the kernel is doing something else. I don't want to use any profiling tools. What approach should I take to write my own C code, which can also run as kernel module if required, to measure time spent accurately. Will it also require to modify the scheduler code? Does /proc gives any statistics in this regard?
Ref: http://stackoverflow.com/questions/2368384/write-a-c-program-to-measure-time...
-- Manavendra Nath Manav _______________________________________________
Hi Victor I was thinking something in these terms: 1) Process is executing a non-critical section like a bottom-half. 2) At Nth line of code, I will measure the timestamp. 3) At (N+1)th line of code, I will voluntarily call schedule() to do context switch. 4) At (N+2)th, I will measure the timestamp, and calculate the time difference. Although the above procedure will measure context switch time statically and not dynamically, it can give a fair idea but for multi-core processors this measurement will heavily deviate from accuracy. If we can set scheduler() process affinity to one single core, will it affect the measurements and predictability of context switches? -- Manavendra Nath Manav