[PATCH v9 0/6] ARM: VDSO
Nathan_Lynch at mentor.com
Fri Sep 5 19:32:49 PDT 2014
On 08/22/2014 04:52 PM, Nathan Lynch wrote:
> Provide fast userspace implementations of gettimeofday and
> clock_gettime on systems that implement the generic timers extension
> defined in ARMv7. This follows the example of arm64 in conception but
> significantly differs in some aspects of the implementation (C vs
> assembly, mainly).
> Clocks supported:
> - CLOCK_REALTIME
> - CLOCK_MONOTONIC
> - CLOCK_REALTIME_COARSE
> - CLOCK_MONOTONIC_COARSE
> This also provides clock_getres (as arm64 does).
> getcpu support is planned but not included at this time.
> For applications to transparently benefit from this change,
> ARM-specific support code needs to be added to glibc. I have such a
> patch, and have verified that glibc's self tests do not detect any
> regressions. I hope to have that code added to glibc for the 2.21
> The VDSO symbols are available for lookup via dlsym even with an
> unpatched glibc.
> Note that while the high-precision realtime and monotonic clock
> support depends on the generic timers extension, support for
> clock_getres and coarse clocks is independent of the timer
> implementation and is provided unconditionally. High-resolution clock
> support requires changes to the arch timer code, posted here:
> The VDSO will function correctly without those changes, but
> gettimeofday and clock_gettime with CLOCK_REALTIME/CLOCK_MONOTONIC
> will not be accelerated.
Russell, what is your current thinking on taking the VDSO patches? I
believe all feedback has been addressed and I was hoping to get it into
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