linux-kernel - Re: [patch 4 15/22] timer: Remove slack leftovers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 22 Jul 2016 17:18:04 +0200
From:	"Jason A. Donenfeld" <Jason@...c4.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Paul 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,
	Rik van Riel <riel@...hat.com>,
	George Spelvin <linux@...encehorizons.net>,
	Len Brown <lenb@...nel.org>,
	Josh Triplett <josh@...htriplett.org>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: [patch 4 15/22] timer: Remove slack leftovers

Hi Thomas,

On Fri, Jul 22, 2016 at 3:04 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
>
> Well, this really depends on the TIMEOUT value you have. The code now does
> implicit batching for larger timeouts by queueing the timers into wheels with
> coarse grained granularity. As long as your new TIMEOUT value ends up in the
> same bucket then that's equivalent to the slack thing.
>
> Can you give me a ballpark of your TIMEOUT value?

Generally either 5 seconds, 10 seconds, or 25 seconds.

Are these okay? Is the 25 case substantially different from the 5 case?


> When you take the slow (queueing) path, it's still expensive, not as bad as
> the previous one, but not really cheap either.

Hmm, okay.