Re: [PATCH 2/3] x86/vdso: Allow clock specific mult and shift values

From: Thomas Gleixner
Date: Mon Apr 15 2019 - 05:51:49 EST


On Mon, 15 Apr 2019, Huw Davies wrote:

> On Sun, Apr 14, 2019 at 12:53:32PM +0200, Thomas Gleixner wrote:
> > So it stays in the same cache line, but as we move the VDSO to generic
> > code, the mask field needs to stay and this will make basetime[CLOCK_MONOTONIC]
> > overlap into the next cache line.
>
> Thanks for the great review; this is a good point.
>
> > See https://lkml.kernel.org/r/alpine.DEB.2.21.1902231727060.1666@xxxxxxxxxxxxxxxxxxxxxxx
> > for an alternate solution to this problem, which avoids this and just gives
> > CLOCK_MONOTONIC_RAW a separate storage space alltogether.
>
> I can certainly do this for the x86 vdso. Would that be useful or
> should I wait for Vincenzo's work on the generic vdso first?

Depends. If Vincenzo comes along with his new version soon, then you might
get this for free :)

Vincenzo, what's the state of your work?

Thanks,

tglx