linux-kernel - Re: [PATCH] maximum latency tracking infrastructure (version 3)

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:	Mon, 28 Aug 2006 18:11:45 +0200
From:	Andreas Mohr <andi@...x01.fht-esslingen.de>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org, akpm@...l.org, mingo@...e.hu,
	jesse.barnes@...el.com, dwalker@...sta.com
Subject: Re: [PATCH] maximum latency tracking infrastructure (version 3)

Hi,

On Mon, Aug 28, 2006 at 05:48:00PM +0200, Arjan van de Ven wrote:
> The proposed solution is to have an interface where drivers can
> * announce the maximum latency (in microseconds) that they can deal with
> * modify this latency
> * give up their constraint
> and a function where the code that decides on power saving strategy can query
> the current global desired maximum.

Nifty (aka "dumb") idea: would it make sense to enable drivers to register a
callback "we're going to go idle now" to e.g. let a driver refill or
service its hardware buffers the very moment before idling? That way
a driver could increase its announced latency requirements,
allowing longer idle sleeps until a hardware buffer overflows or whatever
(but in many cases a hardware service issue would be covered by an IRQ then).

However the time scales involved here (a couple of microseconds per sleep
or so versus a possibly comparably big amount of processing time per callback)
could render such a thing impractical, especially when multiple drivers
and thus multiple callbacks are involved (one might need to watch
total callback processing time then).

Andreas Mohr
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/