Re: [PATCH 2/2] Add a thread cpu time implementation to vDSO

[john stultz]

On Mon, 2011-12-12 at 11:36 -0800, Arun Sharma wrote:
> From: Kumar Sundararajan <kumar@xxxxxx>
> 
> This primarily speeds up clock_gettime(CLOCK_THREAD_CPUTIME_ID, ..)
> via a new vsyscall. We also add a direct vsyscall that returns
> time in ns (RFC: the direct vsyscall doesn't have a corresponding
> regular syscall, although clock_gettime() is pretty close).

I'm still not super psyched about providing a vdso-only API.

If a nanosecond interface like thread_cpu_time() is actually a big win
over clock_gettime(CLOCK_THREAD_CPUTIME,...) it seems it should have its
own syscall as well, no? 

Possibly something like clock_gettime_ns(), which would return the same
values as clock_gettime() but in nanoseconds rather then a timespec?

thanks
-john


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