Re: A few questions and issues with dynticks, NOHZ and powertop

From: Arjan van de Ven
Date: Sun Apr 04 2010 - 23:42:58 EST

On 4/4/2010 3:47, Dominik Brodowski wrote:

On Sat, Apr 03, 2010 at 04:53:26PM -0700, Dmitry Torokhov wrote:
On Sun, Apr 04, 2010 at 12:33:28AM +0200, Dominik Brodowski wrote:

4) SynPS/2 touchpad:
Why does moving the touchpad lead to sooo many IRQs? I can't look as fast
as the mouse pointer seems to get new data:
62,5% (473,1)<interrupt> : PS/2 keyboard/mouse/touchpad

80 pps @ 6 bytes/packet = 480 interrupts/sec.

You can try using psmouse.rate=40 to limit it to 40 pps which should
bring it to the rate of standard PS/2 mouse at the expense of

as a sidenote: if we know -- like here -- that the next IRQ will be issued
soon, in approximately 1.75 ms (well, at least on my system), might it make
sense to make tick_nohz_get_sleep_length() smarter to know about this?

yes and no.

if you are very sure (95%+ or so) then absolutely it needs to know about this
so that the C state selection code can make a better decision.
Right now it tries to look at history to guess this delay.

Unfortunately we do not currently have such a concept in the code to make this
work... but it'd be really nice to have.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at