Re: [RFC PATCH 16/22 -v2] add get_monotonic_cycles

Steven Rostedt
2008-01-17T03:39:25Z

On Thu, 17 Jan 2008, Paul Mackerras wrote:
>
> It's very hard to do a per-thread counter in the VDSO, since threads
> in the same process see the same memory, by definition. You'd have to
> have an array of counters and have some way for each thread to know
> which entry to read. Also you'd have to find space for tens or
> hundreds of thousands of counters, since there can be that many
> threads in a process sometimes.

I was thinking about this. What would also work is just the ability to
read the schedule counter for the current cpu. Now this would require that
the task had a way to know which CPU it was currently on.

-- Steve