Re: [PATCH v4 07/14] clocksource: mips-gic-timer: Always use cluster 0 counter as clocksource

[Thomas Bogendoerfer]

On Tue, Jul 09, 2024 at 04:44:30PM +0200, Daniel Lezcano wrote:
> On 09/07/2024 10:53, Thomas Bogendoerfer wrote:
> > On Tue, Jul 09, 2024 at 09:47:52AM +0800, Jiaxun Yang wrote:
> > > 
> > > 
> > > 在2024年7月9日七月 上午12:36，Daniel Lezcano写道：
> > > > On 11/05/2024 12:43, Aleksandar Rikalo wrote:
> > > > > From: Paul Burton <paulburton@xxxxxxxxxx>
> > > > > 
> > > > > In a multi-cluster MIPS system we have multiple GICs - one in each
> > > > > cluster - each of which has its own independent counter. The counters in
> > > > > each GIC are not synchronised in any way, so they can drift relative to
> > > > > one another through the lifetime of the system. This is problematic for
> > > > > a clocksource which ought to be global.
> > > > > 
> > > > > Avoid problems by always accessing cluster 0's counter, using
> > > > > cross-cluster register access. This adds overhead so we only do so on
> > > > > systems where we actually have CPUs present in multiple clusters.
> > > > > For now, be extra conservative and don't use gic counter for vdso or
> > > > > sched_clock in this case.
> > > > > 
> > > > > Signed-off-by: Paul Burton <paulburton@xxxxxxxxxx>
> > > > > Signed-off-by: Chao-ying Fu <cfu@xxxxxxxxxxxx>
> > > > > Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@xxxxxxxxxx>
> > > > > Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@xxxxxxxxxx>
> > > > > ---
> > > > 
> > > > Applied patch 7 and 8
> > > 
> > > I think it won't compile without patch 1 being applid.
> > > 
> > > Thomas, do you mind to apply patch 1 for now? Given that it's just some extra
> > > function definitions.
> > 
> > no problem, I've applied patch 1 und 2 to mips-next.
> 
> Usually we create a shared immutable branch, but as we are close to the PR,
> I propose I ack these two patches and let them go through the mips tree this
> time

works for me, as well.

Thomas.

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