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From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Mark Salyzyn <salyzyn@android.com>
Cc: John Stultz <john.stultz@linaro.org>,
	lkml <linux-kernel@vger.kernel.org>,
	James Morse <james.morse@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Dmitry Safonov <dsafonov@virtuozzo.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Laura Abbott <labbott@redhat.com>,
	Kees Cook <keescook@chromium.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Andy Gross <andy.gross@linaro.org>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Andrew Pinski <apinski@cavium.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Jeremy Linton <Jeremy.Linton@arm.com>
Subject: Re: RESEND and REBASE arm+arm64+aarch32 vdso rewrite
Date: Tue, 2 Oct 2018 09:50:41 +0100	[thread overview]
Message-ID: <20181002085041.GV30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <8c09a380-7bc8-a353-aeb7-6591e6c57f68@android.com>

On Mon, Oct 01, 2018 at 01:44:52PM -0700, Mark Salyzyn wrote:
> Despite the gain of 0.4% for screen-on battery life, where Android has a mix
> of 64 and 32 bit applications, thus still relevant _today_ on 64 bit
> architectures (providing vDSO32 for 32-bit applications).

I don't think the issue is what you think it is.  0.4% gain is
equivalent to almost (but not quite) 1 minute extra for a lifetime of
4 hours.  Is that really noticable, and is it worth the churn from
merging this series?

Given that the gain is so marginal, I can see why people find it
difficult to get excited about this series to spend the time reviewing
it.

What I'm saying is that the reason that people should look at this
series hasn't been "sold" particularly well.  How does it look from
the system performance point of view - is there a speed-up there
that's more significant?

In any case, I suspect that if you compare the battery life from
kernels from two years ago with modern kernels, you'll see a
degredation over that period just because of the progressive
increase in complexity, and especially things such as the Spectre
work-arounds.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

  parent reply	other threads:[~2018-10-02  8:50 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01 17:58 RESEND and REBASE arm+arm64+aarch32 vdso rewrite Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 01/12] arm: vdso: rename vdso_datapage variables Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 02/12] arm: vdso: add include file defining __get_datapage() Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 03/12] arm: vdso: inline assembler operations to compiler.h Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 04/12] arm: vdso: do calculations outside reader loops Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v6 05/12] arm: vdso: Add support for CLOCK_MONOTONIC_RAW Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 06/12] arm: vdso: add support for clock_getres Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 07/12] arm: vdso: disable profiling Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 08/12] arm: vdso: Add ARCH_CLOCK_FIXED_MASK Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 09/12] arm: vdso: move vgettimeofday.c to lib/vdso/ Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 10/12] arm64: vdso: replace gettimeofday.S with global vgettimeofday.C Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v6 11/12] lib: vdso: Add support for CLOCK_BOOTTIME Mark Salyzyn
2018-10-01 18:15   ` Thomas Gleixner
2018-10-01 20:52     ` Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v5 12/12] lib: vdso: do not expose gettimeofday, if no arch supported timer Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH] lib: vdso: add support for time Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v3 1/3] arm64: compat: Split the sigreturn trampolines and kuser helpers (C sources) Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v3 2/3] arm64: compat: Split the sigreturn trampolines and kuser helpers (assembler sources) Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v3 3/3] arm64: compat: Add CONFIG_KUSER_HELPERS Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH] arm64: compat: Expose offset to registers in sigframes Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH 1/6] arm64: compat: Use vDSO sigreturn trampolines if available Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH 2/6] arm64: elf: Set AT_SYSINFO_EHDR in compat processes Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH 3/6] arm64: Refactor vDSO init/setup Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v2 4/6] arm64: compat: Add a 32-bit vDSO Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH 5/6] arm64: compat: 32-bit vDSO setup Mark Salyzyn
2018-10-01 17:58 ` RESEND [PATCH v2 6/6] arm64: Wire up and expose the new compat vDSO Mark Salyzyn
2018-10-01 18:49 ` RESEND and REBASE arm+arm64+aarch32 vdso rewrite John Stultz
2018-10-01 20:44   ` Mark Salyzyn
2018-10-01 21:28     ` John Stultz
2018-10-02  8:50     ` Russell King - ARM Linux [this message]
2018-10-02 14:53       ` Mark Salyzyn
2018-10-02 10:00     ` Catalin Marinas
2018-10-02 15:09       ` Mark Salyzyn

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