linux-kernel - Re: [PATCH] atmel_tc clocksource/clockevent code

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:	Wed, 5 Mar 2008 17:45:34 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Remy Bohmer <linux@...mer.net>
cc:	David Brownell <david-b@...bell.net>,
	Haavard Skinnemoen <hskinnemoen@...el.com>,
	akpm@...ux-foundation.org, LKML <linux-kernel@...r.kernel.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Nicolas Ferre <nicolas.ferre@....atmel.com>,
	Andrew Victor <linux@...im.org.za>,
	john stultz <johnstul@...ibm.com>
Subject: Re: [PATCH] atmel_tc clocksource/clockevent code

On Wed, 5 Mar 2008, Remy Bohmer wrote:
> Hello David,
> 
> > Could you elaborate on where that 50-100 usec gets spent?
> 
> Attached I have put a screendump of my ETM debugger. It shows a
> complete flow of kernel function-calls of what happens on a timer
> interrupt. In this example the complete sequence takes about 154 us.
> Notice that the ETM is non-intrusive, and that the times are real and
> accurate in this trace. (you can even see the effects of CPU-caches,
> sometimes the same code just runs faster)

Is there any chance to convert this to a text table? Following that
png is pretty hard.

> So, hires timestamps -> really really welcome.
> hires timers -> there should be a (configurable) minimal resolution
> that fits the hardware to not overload the CPU.

clockevents let you set a minimum delta already. This can be set at
runtime before registering the device.

Thanks,

	tglx
--
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/