Re: [patch] TASK_NONINTERACTIVE (was: Machine Freezes while Running Crossover Office)

Pekka Enberg
2005-10-17T15:11:06Z

Ingo,

On Wed, 2005-06-01 at 09:35 +0200, Ingo Molnar wrote:
> Pekka, could you check whether the patch below solves your Wine problem
> (without hurting interactivity otherwise)?

Any chance of getting this merged to the mainline? I am on 2.6.13.4 now
and I still need to manually apply this patch to make Crossover Office
usable. I can confirm that it fixes the problem without introducing any
interactivity regressions as I have been running this for the past four
months or so.

Pekka

>
> ----
>
> this patch implements a task state bit (TASK_NONINTERACTIVE), which can
> be used by blocking points to mark the task's wait as "non-interactive".
> This does not mean the task will be considered a CPU-hog - the wait will
> simply not have an effect on the waiting task's priority - positive or
> negative alike. Right now only pipe_wait() will make use of it, because
> it's a common source of not-so-interactive waits (kernel compilation
> jobs, etc.).
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>
> --- linux/fs/pipe.c.orig
> +++ linux/fs/pipe.c
> @@ -39,7 +39,11 @@ void pipe_wait(struct inode * inode)
> {
> DEFINE_WAIT(wait);
>
> - prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
> + /*
> + * Pipes are system-local resources, so sleeping on them
> + * is considered a noninteractive wait:
> + */
> + prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE|TASK_NONINTERACTIVE);
> up(PIPE_SEM(*inode));
> schedule();
> finish_wait(PIPE_WAIT(*inode), &wait);
> --- linux/kernel/sched.c.orig
> +++ linux/kernel/sched.c
> @@ -1085,6 +1085,16 @@ out_activate:
> }
>
> /*
> + * Tasks that have marked their sleep as noninteractive get
> + * woken up without updating their sleep average. (i.e. their
> + * sleep is handled in a priority-neutral manner, no priority
> + * boost and no penalty.)
> + */
> + if (old_state & TASK_NONINTERACTIVE)
> + __activate_task(p, rq);
> + else
> + activate_task(p, rq, cpu == this_cpu);
> + /*
> * Sync wakeups (i.e. those types of wakeups where the waker
> * has indicated that it will leave the CPU in short order)
> * don't trigger a preemption, if the woken up task will run on
> @@ -1092,7 +1102,6 @@ out_activate:
> * the waker guarantees that the freshly woken up task is going
> * to be considered on this CPU.)
> */
> - activate_task(p, rq, cpu == this_cpu);
> if (!sync || cpu != this_cpu) {
> if (TASK_PREEMPTS_CURR(p, rq))
> resched_task(rq->curr);
> --- linux/include/linux/sched.h.orig
> +++ linux/include/linux/sched.h
> @@ -112,6 +112,7 @@ extern unsigned long nr_iowait(void);
> #define TASK_TRACED 8
> #define EXIT_ZOMBIE 16
> #define EXIT_DEAD 32
> +#define TASK_NONINTERACTIVE 64
>
> #define __set_task_state(tsk, state_value) \
> do { (tsk)->state = (state_value); } while (0)