From: "Paul E. McKenney" <paulmck@kernel.org>
To: Elad Lahav <e2lahav@gmail.com>
Cc: perfbook@vger.kernel.org
Subject: Re: [PATCH 2/2] CodeSamples: Switch ARM64 get_timestamp() to use the hardware counter
Date: Tue, 16 Aug 2022 12:09:06 -0700 [thread overview]
Message-ID: <20220816190906.GF2125313@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <66962abc-94ce-b9ab-e75f-92d8bd03e8c9@gmail.com>
On Tue, Aug 16, 2022 at 08:48:54AM -0400, Elad Lahav wrote:
> On 2022-08-16 08:46, Elad Lahav wrote:
> > Signed-off-by: Elad Lahav <e2lahav@gmail.com>
Queued and pushed, thank you!
> I tested the change on an aarch64 board on both QNX and Linux. The Linux
> results show quite the change in performance from the clock_gettime()
> version, which is probably expected.
>
> Before:
> root@localhost:~/src/CodeSamples/defer# ./gettimestamp
> d3f5e50a7d
> d3f5e50af5 120
> d3f5e50b6d 120
> d3f5e50be5 120
> d3f5e50c5d 120
> d3f5e50cd5 120
> d3f5e50d25 80
> d3f5e50d9d 120
> d3f5e50e15 120
> d3f5e50e8d 120
>
> After:
> root@localhost:~/src/CodeSamples/defer# ./gettimestamp
> 73706dac1
> 73706dac2 1
> 73706dac4 2
> 73706dac5 1
> 73706dac6 1
> 73706dac8 2
> 73706dac9 1
> 73706dacb 2
> 73706dacc 1
> 73706dacd 1
I have to ask... Are these the same units? (I have in the past used
hardware where they would not be.)
Anyway, even if the hardware clock ticks an order of magnitude more
slowly, it is an impressive speedup. ;-)
Thanx, Paul
prev parent reply other threads:[~2022-08-16 19:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 12:46 [PATCH 2/2] CodeSamples: Switch ARM64 get_timestamp() to use the hardware counter Elad Lahav
2022-08-16 12:48 ` Elad Lahav
2022-08-16 19:09 ` Paul E. McKenney [this message]
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