From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Santosh Sivaraj <santosh@fossix.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
John Stultz <john.stultz@linaro.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE
Date: Tue, 12 Dec 2017 22:39:22 +1100 (AEDT) [thread overview]
Message-ID: <3ywyXW1GZ6z9sPm@ozlabs.org> (raw)
In-Reply-To: <20171016054914.24832-1-santosh@fossix.org>
On Mon, 2017-10-16 at 05:49:14 UTC, Santosh Sivaraj wrote:
> Current vDSO64 implementation does not have support for coarse clocks
> (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back
> to system call, increasing the response time, vDSO implementation reduces
> the cycle time. Below is a benchmark of the difference in execution times.
>
> (Non-coarse clocks are also included just for completion)
>
> clock-gettime-realtime: syscall: 172 nsec/call
> clock-gettime-realtime: libc: 28 nsec/call
> clock-gettime-realtime: vdso: 22 nsec/call
> clock-gettime-monotonic: syscall: 171 nsec/call
> clock-gettime-monotonic: libc: 30 nsec/call
> clock-gettime-monotonic: vdso: 25 nsec/call
> clock-gettime-realtime-coarse: syscall: 153 nsec/call
> clock-gettime-realtime-coarse: libc: 16 nsec/call
> clock-gettime-realtime-coarse: vdso: 10 nsec/call
> clock-gettime-monotonic-coarse: syscall: 167 nsec/call
> clock-gettime-monotonic-coarse: libc: 17 nsec/call
> clock-gettime-monotonic-coarse: vdso: 11 nsec/call
>
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/5c929885f1bb4b77f85b1769c49405
cheers
prev parent reply other threads:[~2017-12-12 11:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 5:49 [PATCH v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj
2017-12-12 11:39 ` Michael Ellerman [this message]
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