From: Lee Revell <rlrevell@joe-job.com>
To: Len Brown <len.brown@intel.com>
Cc: Tim Schmielau <tim@physik3.uni-rostock.de>,
john stultz <johnstul@us.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
george anzinger <george@mvista.com>
Subject: Re: gradual timeofday overhaul
Date: Wed, 20 Oct 2004 13:09:29 -0400 [thread overview]
Message-ID: <1098292168.1429.96.camel@krustophenia.net> (raw)
In-Reply-To: <1098258460.26595.4320.camel@d845pe>
On Wed, 2004-10-20 at 03:47, Len Brown wrote:
> The current design with HZ=1000 gives us 1ms = 1000usec between clock
> ticks. But some platforms take nearly that long just to enter/exit low
> power states; which means that on Linux the hardware pays a long idle
> state exit latency (performance hit) but gets little or no power savings
> from the time it resides in that idle state.
My testing shows that the timer interrupt runs for about 21 usec.
That's 2.1% of its time just running the timer ISR! No wonder this
causes PM issues, 2.1% cpu load is not exactly an idle machine. This is
a 600Mhz C3, so on a slower embedded system this might be 5%.
So, any solution that would allow high res timers with Hz = 100 would be
welcome.
Lee
next prev parent reply other threads:[~2004-10-20 17:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-19 18:21 process start time set wrongly at boot for kernel 2.6.9 Jerome Borsboom
2004-10-19 20:11 ` john stultz
2004-10-20 0:42 ` Tim Schmielau
2004-10-20 0:59 ` john stultz
2004-10-20 3:05 ` gradual timeofday overhaul Tim Schmielau
2004-10-20 7:47 ` Len Brown
2004-10-20 15:09 ` George Anzinger
2004-10-20 15:59 ` Richard B. Johnson
2004-10-20 15:17 ` George Anzinger
2004-10-20 17:09 ` Lee Revell [this message]
2004-10-20 21:42 ` Len Brown
2004-10-20 18:13 ` john stultz
2004-10-20 14:51 ` process start time set wrongly at boot for kernel 2.6.9 George Anzinger
2004-10-20 17:42 ` john stultz
2004-10-20 23:52 ` George Anzinger
2004-10-21 0:25 ` john stultz
2004-10-21 1:04 ` George Anzinger
2004-10-27 7:55 ` Tim Schmielau
2004-10-21 8:32 gradual timeofday overhaul Perez-Gonzalez, Inaky
2004-10-21 21:17 ` George Anzinger
2004-10-21 22:40 ` Chris Friesen
2004-10-25 23:12 ` George Anzinger
2004-10-25 23:51 ` Chris Friesen
2004-10-21 21:32 Perez-Gonzalez, Inaky
2004-10-21 22:36 ` Chris Friesen
2004-10-22 0:21 ` George Anzinger
2004-10-22 0:29 Perez-Gonzalez, Inaky
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