From: Will Deacon <will@kernel.org>
To: Mark Salyzyn <salyzyn@android.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
Chiawei Wang <chiaweiwang@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Enrico Weigelt <info@metux.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alexios Zavras <alexios.zavras@intel.com>,
linux-arm-kernel@lists.infradead.org,
Allison Randal <allison@lohutok.net>
Subject: Re: [PATCH v2]: arch: arm64: vdso: export the symbols for time()
Date: Tue, 23 Jun 2020 15:44:59 +0100 [thread overview]
Message-ID: <20200623144459.GB4336@willie-the-truck> (raw)
In-Reply-To: <20200615143838.143137-1-salyzyn@android.com>
On Mon, Jun 15, 2020 at 07:38:24AM -0700, Mark Salyzyn wrote:
> From: Chiawei Wang <chiaweiwang@google.com>
>
> __cvdso_time() can be found in vDSO implementation,
> but the symbols for time() are not exported.
>
> Export the symbols and run bionic-benchmarks.
>
> BEFORE:
> bionic-benchmarks32 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 83.6 ns 83.5 ns 8385964
>
> bionic-benchmarks64 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 63.5 ns 63.4 ns 11037509
>
> AFTER:
> bionic-benchmarks32 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 8.57 ns 8.56 ns 81887312
>
> bionic-benchmarks64 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 7.52 ns 7.51 ns 93253809
>
> Signed-off-by: Chiawei Wang <chiaweiwang@google.com>
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@android.com
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Enrico Weigelt <info@metux.net>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Alexios Zavras <alexios.zavras@intel.com>
> Cc: linux-arm-kernel@lists.infradead.org
I don't understand this: neither arm nor arm64 offer the time() syscall
afaict, so the C library should be implementing it in terms of
clock_gettime() anyway, which _is_ implemented in the vDSO.
What's am I missing?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: Mark Salyzyn <salyzyn@android.com>
Cc: Enrico Weigelt <info@metux.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Allison Randal <allison@lohutok.net>,
linux-kernel@vger.kernel.org,
Alexios Zavras <alexios.zavras@intel.com>,
Chiawei Wang <chiaweiwang@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
kernel-team@android.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2]: arch: arm64: vdso: export the symbols for time()
Date: Tue, 23 Jun 2020 15:44:59 +0100 [thread overview]
Message-ID: <20200623144459.GB4336@willie-the-truck> (raw)
In-Reply-To: <20200615143838.143137-1-salyzyn@android.com>
On Mon, Jun 15, 2020 at 07:38:24AM -0700, Mark Salyzyn wrote:
> From: Chiawei Wang <chiaweiwang@google.com>
>
> __cvdso_time() can be found in vDSO implementation,
> but the symbols for time() are not exported.
>
> Export the symbols and run bionic-benchmarks.
>
> BEFORE:
> bionic-benchmarks32 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 83.6 ns 83.5 ns 8385964
>
> bionic-benchmarks64 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 63.5 ns 63.4 ns 11037509
>
> AFTER:
> bionic-benchmarks32 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 8.57 ns 8.56 ns 81887312
>
> bionic-benchmarks64 --bionic_extra BM_time_time
> -----------------------------------------------------
> Benchmark Time CPU Iterations
> -----------------------------------------------------
> BM_time_time 7.52 ns 7.51 ns 93253809
>
> Signed-off-by: Chiawei Wang <chiaweiwang@google.com>
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@android.com
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Enrico Weigelt <info@metux.net>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Alexios Zavras <alexios.zavras@intel.com>
> Cc: linux-arm-kernel@lists.infradead.org
I don't understand this: neither arm nor arm64 offer the time() syscall
afaict, so the C library should be implementing it in terms of
clock_gettime() anyway, which _is_ implemented in the vDSO.
What's am I missing?
Will
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next prev parent reply other threads:[~2020-06-23 14:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 14:38 [PATCH v2]: arch: arm64: vdso: export the symbols for time() Mark Salyzyn
2020-06-15 14:38 ` Mark Salyzyn
2020-06-23 14:44 ` Will Deacon [this message]
2020-06-23 14:44 ` Will Deacon
[not found] ` <CAJ-C09j3ZZOZDPLiS+8-9Ypd1hYtfJY5LUym8z79xAUKS11VUA@mail.gmail.com>
2020-06-23 16:57 ` Will Deacon
2020-06-23 16:57 ` Will Deacon
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