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

From: Daniel Lezcano
Date: Tue Jul 09 2024 - 10:46:23 EST


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

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