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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	linux-kselftest@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Huw Davies <huw@codeweavers.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Will Deacon <will.deacon@arm.com>,
	Russell King <linux@armlinux.org.uk>,
	Ralf Baechle <ralf@linux-mips.org>,
	Mark Salyzyn <salyzyn@android.com>,
	Paul Burton <paul.burton@mips.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Collingbourne <pcc@google.com>
Subject: Re: [PATCH v6 00/19] Unify vDSOs across more architectures
Date: Fri, 21 Jun 2019 10:11:58 +0100
Message-ID: <40c3e4e9-96d3-f940-f5cb-ed97762ef9b0@arm.com> (raw)
In-Reply-To: <20190620172746.7f92cb14@donnerap.cambridge.arm.com>

On 20/06/2019 17:27, Andre Przywara wrote:
> On Thu, 30 May 2019 15:15:12 +0100
> Vincenzo Frascino <vincenzo.frascino@arm.com> wrote:
> 
> Hi,
> 
>> vDSO (virtual dynamic shared object) is a mechanism that the Linux
>> kernel provides as an alternative to system calls to reduce where
>> possible the costs in terms of cycles.
>> [ ... ]
>> The porting has been benchmarked and the performance results are
>> provided as part of this cover letter.
> 
> I can't reveal the absolute numbers here, but vdsotest-bench gives me
> quite some performance gain on my board here ("time needed on v6" divided
> by "time needed on 5.2-rc1", so smaller percentages are better):
> clock-gettime-monotonic:	23 %
> clock-gettime-monotonic-raw:	30 %
> clock-gettime-tai:		 5 %
> clock-getres-tai:		 5 %
> clock-gettime-boottime:		 5 %
> clock-getres-boottime:		 5 %
> clock-gettime-realtime:		25 %
> gettimeofday:			26 % 
> The other numbers stayed the same or differed by just 1 ns, which seems to
> be within the margin of error, as repeated runs on the same kernel suggest.
> The 5% numbers are of course those were we went from a syscall-only to the
> newly added arm64 VDSO implementation, but even the other calls improved
> by a factor of 3 or more.
> 
> Sounds like a strong indicator that this is a good thing to have.
> 
> Not sure if "running some benchmark a couple of times on a single machine"
> qualifies for this, but I guess it means:
> 
> Tested-by: Andre Przywara <andre.przywara@arm.com>
>

Thanks Andre, it sounds great! I will add your tag as well to my patches.

> Cheers,
> Andre.
> 

-- 
Regards,
Vincenzo

      reply index

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-30 14:15 Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 01/19] kernel: Standardize vdso_datapage Vincenzo Frascino
2019-05-31  8:16   ` Arnd Bergmann
2019-06-04 12:05     ` Vincenzo Frascino
2019-06-10 17:47       ` Huw Davies
2019-06-10  9:27   ` Huw Davies
2019-06-10 10:17     ` Vincenzo Frascino
2019-06-10 10:31       ` Huw Davies
2019-06-10 11:07         ` Vincenzo Frascino
2019-06-10 11:37           ` Huw Davies
2019-05-30 14:15 ` [PATCH v6 02/19] kernel: Define gettimeofday vdso common code Vincenzo Frascino
2019-05-31  8:19   ` Arnd Bergmann
2019-06-04 12:08     ` Vincenzo Frascino
2019-06-10  9:31   ` Huw Davies
2019-06-10 10:18     ` Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 03/19] kernel: Unify update_vsyscall implementation Vincenzo Frascino
2019-06-10  9:34   ` Huw Davies
2019-06-10 10:19     ` Vincenzo Frascino
2019-06-14 11:10   ` Thomas Gleixner
2019-06-14 12:15     ` Vincenzo Frascino
2019-06-14 12:19       ` Thomas Gleixner
2019-06-14 12:25         ` Vincenzo Frascino
2019-06-14 13:07           ` Thomas Gleixner
2019-05-30 14:15 ` [PATCH v6 04/19] arm64: Substitute gettimeofday with C implementation Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 05/19] arm64: Build vDSO with -ffixed-x18 Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 06/19] arm64: compat: Add missing syscall numbers Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 07/19] arm64: compat: Expose signal related structures Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 08/19] arm64: compat: Generate asm offsets for signals Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 09/19] lib: vdso: Add compat support Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 10/19] arm64: compat: Add vDSO Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 11/19] arm64: Refactor vDSO code Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 12/19] arm64: compat: vDSO setup for compat layer Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 13/19] arm64: elf: vDSO code page discovery Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 14/19] arm64: compat: Get sigreturn trampolines from vDSO Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 15/19] arm64: Add vDSO compat support Vincenzo Frascino
2019-06-01  9:38   ` Catalin Marinas
2019-06-04 12:10     ` Vincenzo Frascino
2019-05-30 14:15 ` [PATCH v6 16/19] arm: Add support for generic vDSO Vincenzo Frascino
2019-05-31  8:32   ` Arnd Bergmann
2019-05-30 14:15 ` [PATCH v6 17/19] mips: " Vincenzo Frascino
2019-05-31  8:34   ` Arnd Bergmann
2019-06-03 14:54     ` Mark Salyzyn
2019-06-03 17:07       ` Arnd Bergmann
2019-05-30 14:15 ` [PATCH v6 18/19] x86: " Vincenzo Frascino
2019-05-30 15:41   ` Michael Kelley
2019-06-04 12:13     ` Vincenzo Frascino
2019-06-14 11:15     ` Thomas Gleixner
2019-06-14 21:17       ` Sasha Levin
2019-06-22 14:46         ` Thomas Gleixner
2019-06-23 19:09           ` Sasha Levin
2019-06-23 21:58             ` Stephen Rothwell
2019-06-24  0:24               ` Sasha Levin
2019-06-24  1:20                 ` Stephen Rothwell
2019-06-23 22:12             ` Thomas Gleixner
2019-06-24  0:04               ` Michael Kelley
2019-06-24  0:25                 ` Thomas Gleixner
2019-06-28 18:40                   ` Michael Kelley
2019-05-30 14:15 ` [PATCH v6 19/19] kselftest: Extend vDSO selftest Vincenzo Frascino
2019-05-31  8:53   ` Arnd Bergmann
2019-05-31  8:46 ` [PATCH v6 00/19] Unify vDSOs across more architectures Arnd Bergmann
2019-06-04 12:04   ` Vincenzo Frascino
2019-06-04 12:12     ` Arnd Bergmann
2019-06-05 14:32       ` Vincenzo Frascino
2019-06-14 12:16     ` Thomas Gleixner
2019-06-14 12:19       ` Vincenzo Frascino
2019-06-20  6:17 ` Shijith Thotton
2019-06-20  8:55   ` Vincenzo Frascino
2019-06-20 16:27 ` Andre Przywara
2019-06-21  9:11   ` Vincenzo Frascino [this message]

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