From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/3] xen/arm: set the system time in Xen via the XENPF_settime hypercall
Date: Mon, 09 Nov 2015 21:45:50 +0100 [thread overview]
Message-ID: <5034618.DZpKjPX0Jn@wuerfel> (raw)
In-Reply-To: <alpine.DEB.2.02.1511091741480.23825@kaball.uk.xensource.com>
On Monday 09 November 2015 17:42:50 Stefano Stabellini wrote:
> On Mon, 9 Nov 2015, Stefano Stabellini wrote:
> > On Mon, 9 Nov 2015, Arnd Bergmann wrote:
> > > On Monday 09 November 2015 14:10:22 Stefano Stabellini wrote:
> > >
> > > Just to make sure that this is actually the correct interface
> > > that you want to call:
> > >
> > > __current_kernel_time{,64}() is the fastest interface we have
> > > to get an approximation of the current time, while ignoring
> > > all of the locking.
> > >
> > > Is is possible that you instead want ktime_get_real_ts64(),
> > > which gives you the time as precise as the kernel knows it,
> > > but uses locking?
> >
> > I am not 100% sure. Can I call ktime_get_real_ts64 from a
> > pvclock_gtod notifier_call function?
>
> It doesn't look like it: we would be getting the tk_core seqcount twice.
Ok, I see. I'm still unsure what this is all good for, but at
least this call appears to be safe.
Arnd
prev parent reply other threads:[~2015-11-09 20:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-05 17:09 [PATCH 0/3] Xen wallclock on arm and arm64 Stefano Stabellini
2015-11-05 17:09 ` [PATCH 1/3] xen/arm: introduce xen_read_wallclock Stefano Stabellini
2015-11-05 18:53 ` Arnd Bergmann
2015-11-06 15:09 ` Stefano Stabellini
2015-11-06 15:56 ` Arnd Bergmann
2015-11-09 13:53 ` Stefano Stabellini
2015-11-09 16:16 ` Arnd Bergmann
2015-11-09 17:14 ` Stefano Stabellini
2015-11-09 20:42 ` Arnd Bergmann
2015-11-06 12:26 ` Mark Rutland
2015-11-06 14:34 ` Stefano Stabellini
2015-11-05 17:09 ` [PATCH 2/3] xen/arm: introduce HYPERVISOR_dom0_op on arm and arm64 Stefano Stabellini
2015-11-05 17:21 ` [Xen-devel] " Jan Beulich
2015-11-06 14:45 ` Stefano Stabellini
2015-11-05 17:09 ` [PATCH 3/3] xen/arm: set the system time in Xen via the XENPF_settime hypercall Stefano Stabellini
2015-11-05 17:45 ` [Xen-devel] " David Vrabel
2015-11-06 14:59 ` Stefano Stabellini
2015-11-05 18:58 ` Arnd Bergmann
2015-11-09 14:10 ` Stefano Stabellini
2015-11-09 16:10 ` Arnd Bergmann
2015-11-09 17:17 ` Stefano Stabellini
2015-11-09 17:42 ` Stefano Stabellini
2015-11-09 20:45 ` Arnd Bergmann [this message]
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