linux-kernel - Re: [PATCH RESEND] nohz: Restart tick before do softirq

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Message-ID: <20210203131105.GA3666@lothringen>
Date:   Wed, 3 Feb 2021 14:11:05 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     chenshiyan <chenshiyan@...ux.alibaba.com>
Cc:     fweisbec@...il.com, tglx@...utronix.de, mingo@...nel.org,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] nohz: Restart tick before do softirq

On Wed, Feb 03, 2021 at 09:04:05PM +0800, chenshiyan wrote:
> Are you working on an architecture that doesn't implement it?
> -No, we test it on x86.
> 
> The problem is , when it's doing softirq, but there’s no tick, so we don’t know how long 
> It takes. The TOP or some other procs can not show the right value of sirq.

But IRQTIME counting is based on sched_clock() which shouldn't use jiffies
in the case in x86. In fact jiffies based sched_clock() isn't suitable for
IRQTIME at all. So I don't understand the problem.