How is jiffies upation while holding spinlock in Uniprocessor or SMP environment?

From	raghu MG <raghumag@gmail.com>
Newsgroups	linux.kernel
Subject	How is jiffies upation while holding spinlock in Uniprocessor or SMP environment?
Date	2015-10-26 07:50 +0100
Message-ID	<qnJLs-4TL-19@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hello,
I have couple of questions.
1) In case of UP how is jiffies(timer) get updated while holding spin
lock using spinlock_irq_save?

2)My understanding is in smp environment jiffies updation cannot be
done on processor holding spinlock irrespective of spinlock API.So
timer interrupt should be enabled across all cores in SoC. Imagine a
scenario in quad core processor where 4 cores are holding 4 different
spinlocks & how is the timer interrupt for jiffies handled?
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How is jiffies upation while holding spinlock in Uniprocessor or SMP environment? raghu MG <raghumag@gmail.com> - 2015-10-26 07:50 +0100
  Re: How is jiffies upation while holding spinlock in Uniprocessor or  SMP environment? Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-26 11:50 +0100
    Re: How is jiffies upation while holding spinlock in Uniprocessor or  SMP environment? raghu MG <raghumag@gmail.com> - 2015-10-30 12:00 +0100

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