This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [RFC/PATCH] ARM: VDSO support
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 06 Apr 2015 16:04:42 -0300
- Subject: Re: [RFC/PATCH] ARM: VDSO support
- Authentication-results: sourceware.org; auth=none
- References: <1428081934-22419-1-git-send-email-nathan_lynch at codesourcery dot com>
Hi,
On 03-04-2015 14:25, Nathan Lynch wrote:
> Future versions of Linux on 32-bit ARM are expected to provide fast
> user-space implementations of the following system calls:
>
> - gettimeofday
> - clock_gettime
>
> The kernel implementation depends on the ARMv7 Generic Timers
> Extension to accelerate these system calls. So CPUs such as
> Cortex-A15 and -A7 benefit, while Cortex-A9, -A8, and pre-v7 CPUs do
> not.
>
> The kernel support is currently in linux-next and is slated for
> inclusion in Linux 4.1. I plan to ping or resubmit this patch once
> Linux 4.1 is released, but would appreciate any preliminary review in
> the meantime. For reference, the current kernel patch submission may
> be found here:
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/332573.html
>
> This patch adds support for the ARM VDSO to glibc. I have run make
> check on OMAP5 using kernels with and without the VDSO, with no new
> failures.
LGTM. Also, you can tune latency a bit more by using IFUNC on gettimeofday.