Re: [RFC 1/2] timers: Add pending timer bool in struct timer_base
From: Thomas Gleixner <hidden>
Date: 2021-06-18 21:06:13
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Nicolas, On Thu, Jun 10 2021 at 14:59, Nicolas Saenz Julienne wrote: please always Cc the relevant mailing lists and the maintainers. MAINTAINERS exists for a reason.
We need to efficiently check whether a timer base has no pending events.
'We need' is not a technical explanation. That's close to 'I want a pony'. Please describe what you are trying to solve and why the existing mechanisms are not good enough. See Documentation/process/submitting-patches.rst
So introduce a new variable in struct timer_base to do so.
The variable solves your problem? Interesting solution.
base->next_expiry = bucket_expiry; base->next_expiry_recalc = false; +#ifdef CONFIG_PREEMPT_RT + base->pending = true; +#endif
What is RT specific about that?
quoted hunk ↗ jump to hunk
trigger_dyntick_cpu(base, timer); } }@@ -1598,6 +1602,9 @@ static unsigned long __next_timer_interrupt(struct timer_base *base) } base->next_expiry_recalc = false; +#ifdef CONFIG_PREEMPT_RT + base->pending = (next != base->clk + NEXT_TIMER_MAX_DELTA); +#endif
This lacks any information about the semantics of this flag:
- When is it valid and when not?
- What is the valid use case for this flag?
Summary of the supplied information: We need a flag, so we added one.
Sorry that's not sufficient.
Thanks,
tglx