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Message-ID: <alpine.LFD.0.9999.0711252243410.26417@localhost.localdomain>
Date: Sun, 25 Nov 2007 22:51:36 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: "Rafael J. Wysocki" <rjw@...k.pl>
cc: Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...e.hu>,
kernel list <linux-kernel@...r.kernel.org>
Subject: Re: nohz and strange sleep latencies
On Sun, 25 Nov 2007, Rafael J. Wysocki wrote:
> > Digging into process_32|64.c...
> >
> > 64:
> > while (1) {
> > while (!need_resched()) {
> > void (*idle)(void);
> >
> > if (__get_cpu_var(cpu_idle_state))
> > __get_cpu_var(cpu_idle_state) = 0;
> >
> > tick_nohz_stop_sched_tick();
> >
> > 32:
> > while (1) {
> > tick_nohz_stop_sched_tick();
> > while (!need_resched()) {
> > void (*idle)(void);
> >
> > if (__get_cpu_var(cpu_idle_state))
> > __get_cpu_var(cpu_idle_state) = 0;
> >
> > ...eek? Which one is wrong?
>
> Hm, it looks like you should have quoted more lines ...
>
> In the second case (32), the tick_nohz_stop_sched_tick() seems to be
> redundant, so I bet it's this one.
No. Both are fine. the 64bit version calls into
tick_nohz_stop_sched_tick() way to often. This is a leftover from the
old theory that we can have non-irq caused wakeups. Will fix it.
tglx
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