Re: [PATCH -tip-rcu] Make rcutorture more vicious: make quiescent rcutorture less power-hungry

Arjan van de Ven
2008-06-22T20:17:41Z

On Sun, 22 Jun 2008 13:06:38 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:

> This patch makes the non-module rcutorture a bit more friendly to
> the power-conservation code. This is a rather simple-minded approach.
> More sophisticated approaches would get rid of the rcutorture tasks
> while rcutorture execution was suppressed, but attempts thus far to
> do this have not gone well -- calling rcu_torture_init() from a /proc
> callout results in oopses.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
>
> rcutorture.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff -urpNa -X dontdiff
> linux-2.6.26-rc4-rcut2-proc/kernel/rcutorture.c
> linux-2.6.26-rc4-rcut3-procq/kernel/rcutorture.c ---
> linux-2.6.26-rc4-rcut2-proc/kernel/rcutorture.c 2008-06-22
> 10:29:04.000000000 -0700 +++
> linux-2.6.26-rc4-rcut3-procq/kernel/rcutorture.c 2008-06-22
> 12:20:10.000000000 -0700 @@ -196,7 +196,10 @@ static void
> rcu_stutter_wait(void) { while (stutter_pause_test
> || !rcutorture_runnable)
> - schedule_timeout_interruptible(1);
> + if (rcutorture_runnable)
> + schedule_timeout_interruptible(1);
> + else
> + schedule_timeout_interruptible(HZ);
> }

could you also make it use round_jiffies_relative() to make the power
impact even less.....
(by coalescing various "once a second" timers like this)

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