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Date: Mon, 12 Dec 2011 15:09:21 -0800
From: john stultz <johnstul@...ibm.com>
To: Arun Sharma <asharma@...com>
Cc: linux-kernel@...r.kernel.org, Kumar Sundararajan <kumar@...com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...e.hu>,
Thomas Gleixner <tglx@...utronix.de>,
Andy Lutomirski <luto@....EDU>
Subject: Re: [PATCH 2/2] Add a thread cpu time implementation to vDSO
On Mon, 2011-12-12 at 11:36 -0800, Arun Sharma wrote:
> From: Kumar Sundararajan <kumar@...com>
>
> 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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