linux-kernel - Re: [patch 13/20] timer: Switch to a non cascading wheel

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Date:	Mon, 13 Jun 2016 05:46:55 -0700
From:	Eric Dumazet <edumazet@...gle.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Chris Mason <clm@...com>,
	Arjan van de Ven <arjan@...radead.org>, rt@...utronix.de
Subject: Re: [patch 13/20] timer: Switch to a non cascading wheel

On Mon, Jun 13, 2016 at 5:30 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Mon, 13 Jun 2016, Peter Zijlstra wrote:
>> On Mon, Jun 13, 2016 at 08:41:00AM -0000, Thomas Gleixner wrote:
>> > +
>> > +   /* Cascading, sigh... */
>>
>> So given that userspace has no influence on timer period; can't we
>> simply fail to support timers longer than 30 minutes?
>>
>> In anything really arming timers _that_ long?
>
> Unfortunately yes. Networking being one of those. Real cascading happens once
> in a blue moon, but it happens.
>

Anyway, for the more common HZ=1000 case, what would the 'limit' be ?