----- Mail original -----
> De: "Paolo Bonzini" <pbonz...@redhat.com>
> À: "Sebastian Tanase" <sebastian.tan...@openwide.fr>
> Cc: aligu...@amazon.com, afaer...@suse.de, r...@twiddle.net, "peter maydell"
> <peter.mayd...@linaro.org>,
> mich...@walle.cc, a...@alex.org.uk, stefa...@redhat.com,
> lcapitul...@redhat.com, crobi...@redhat.com,
> arm...@redhat.com, wenchaoq...@gmail.com, quint...@redhat.com,
> kw...@redhat.com, m...@redhat.com, "camille begue"
> <camille.be...@openwide.fr>, qemu-devel@nongnu.org
> Envoyé: Mardi 22 Juillet 2014 16:59:18
> Objet: Re: [RFC PATCH V4 0/6] icount: Implement delay algorithm between guest
> and host clocks
>
> Il 22/07/2014 16:02, Sebastian Tanase ha scritto:
> > Yes, QEMU_CLOCK_VIRTUAL counts up from
> > qemu_clock_get_ns(QEMU_CLOCK_REALTIME)
> > on ARM (I have only tested with the versatilepb and vexpress
> > boards).
>
> That's a bug to fix indeed, then---it should count up from 0 without
> icount, and icount shouldn't affect this. Thanks for investigating
> it.
Just to be sure I don't missunderstand, when you say "without icount"
you refer to qemu_icount_bias (aka when the vcpu is inactive), right?
Sebastian
>
> > Supposing the patch that changes vm_clock_warp_start from 0 to -1
> > is accepted,
>
> ... which shouldn't be a problem,... :)
>
> > I could use the information in timers_state.cpu_clock_offset
> > instead of recalculating
> > the offset. Besides, given that I only need this particular field
> > from the whole
> > structure, I think I don't have to make timers_state public; I
> > could add a function
> > in cpus.c, for example:
> >
> > int64_t cpu_get_clock_offset(void)
> > {
> > int64_t ti;
> > unsigned start;
> >
> > do {
> > start =
> > seqlock_read_begin(&timers_state.vm_clock_seqlock);
> > ti = -timers_state.cpu_clock_offset;
> > } while (seqlock_read_retry(&timers_state.vm_clock_seqlock,
> > start));
> >
> > return ti;
> > }
> >
> > that will return the cpu_clock_offset field.
>
> Indeed what I was proposing is a bit more sloppy. If you do that,
> you
> have to make the function a bit more general:
>
> ti = timers_state.cpu_clock_offset;
> if (!timers_state.cpu_ticks_enabled) {
> ti -= get_clock();
> }
> ...
>
> return -ti;
>
> even though in cpus.c you'll only be using it when cpu_ticks_enabled
> is
> true. See cpu_enable_ticks() and cpu_disable_ticks().
>
> Paolo
>
