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SubjectRe: [PATCH] push rounding up of relative request to schedule_timeout()
Hi,

On Thu, 4 Aug 2005, Nishanth Aravamudan wrote:

> > What makes you think the comment is correct? This comment was added at
> > 2.4.3, while schedule_timeout() has this behaviour since it was added at
> > 2.1.127.
>
> Fair enough. Should we change the comment?

It can't hurt to fix the comment.

> If a user requests schedule_timeout(HZ/100); which, if HZ is 1000, is 10
> jiffies, yes? But, since we are between ticks, we want to actually add
> that request to the next interval, not to the current one. Otherwise, we
> do have the possibility of returning early. Currently, we require
> callers to add the +1 to their request, and thus they only add it to the
> first one. The problem with my patch which pushed it to
> schedule_timeout(), is that we will do +1 to every request. I'm not
> sure, without some sort of "persistent" timeout control structure, how
> we get around that, though, in the schedule_timeout() case. Does that
> make any more sense?

I don't disagree, but please create some sane interfaces, e.g. something
like below. This allows to first convert as much as possible
schedule_timeout() users and then we can still change the
schedule_timeout() interface.

bye, Roman

include/linux/sched.h | 17 +++++++++++
kernel/timer.c | 71 +++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 78 insertions(+), 10 deletions(-)
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h 2005-06-18 15:00:59.000000000 +0200
+++ linux-2.6/include/linux/sched.h 2005-08-04 23:42:43.000000000 +0200
@@ -182,9 +182,24 @@ extern void scheduler_tick(void);
extern int in_sched_functions(unsigned long addr);

#define MAX_SCHEDULE_TIMEOUT LONG_MAX
-extern signed long FASTCALL(schedule_timeout(signed long timeout));
+extern void schedule_until(unsigned long expire) fastcall;
+extern int schedule_until_intr(unsigned long expire) fastcall;
+extern int schedule_until_unintr(unsigned long expire) fastcall;
+extern signed long schedule_timeout(signed long timeout) fastcall;
+extern int schedule_timeout_intr(signed long timeout) fastcall;
+extern int schedule_timeout_unintr(signed long timeout) fastcall;
asmlinkage void schedule(void);

+static inline int schedule_timeout_msecs_intr(unsigned int timeout)
+{
+ return schedule_timeout_intr(msecs_to_jiffies(timeout));
+}
+
+static inline int schedule_timeout_msecs_unintr(unsigned int timeout)
+{
+ return schedule_timeout_unintr(msecs_to_jiffies(timeout));
+}
+
struct namespace;

/* Maximum number of active map areas.. This is a random (large) number */
Index: linux-2.6/kernel/timer.c
===================================================================
--- linux-2.6.orig/kernel/timer.c 2005-06-18 15:01:12.000000000 +0200
+++ linux-2.6/kernel/timer.c 2005-08-04 23:42:36.000000000 +0200
@@ -1049,6 +1049,67 @@ static void process_timeout(unsigned lon
wake_up_process((task_t *)__data);
}

+fastcall __sched void schedule_until(unsigned long expire)
+{
+ struct timer_list timer;
+
+ init_timer(&timer);
+ timer.expires = expire;
+ timer.data = (unsigned long) current;
+ timer.function = process_timeout;
+
+ add_timer(&timer);
+ schedule();
+ del_singleshot_timer_sync(&timer);
+}
+EXPORT_SYMBOL(schedule_until);
+
+fastcall __sched int schedule_until_intr(unsigned long expire)
+{
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_until(expire);
+ return time_before(expire, jiffies);
+}
+EXPORT_SYMBOL(schedule_until_intr);
+
+fastcall __sched int schedule_until_unintr(unsigned long expire)
+{
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule_until(expire);
+ return time_before(expire, jiffies);
+}
+EXPORT_SYMBOL(schedule_until_intr);
+
+fastcall __sched int schedule_timeout_intr(signed long timeout)
+{
+ unsigned long expire;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (timeout >= MAX_SCHEDULE_TIMEOUT - 1) {
+ schedule();
+ return 1;
+ }
+ expire = jiffies + timeout + 1;
+ schedule_until(expire);
+ return time_before(expire, jiffies);
+}
+EXPORT_SYMBOL(schedule_timeout_intr);
+
+fastcall __sched int schedule_timeout_unintr(signed long timeout)
+{
+ unsigned long expire;
+
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (timeout >= MAX_SCHEDULE_TIMEOUT - 1) {
+ schedule();
+ return 1;
+ }
+ expire = jiffies + timeout + 1;
+ schedule_until(expire);
+ return time_before(expire, jiffies);
+}
+EXPORT_SYMBOL(schedule_timeout_unintr);
+
/**
* schedule_timeout - sleep until timeout
* @timeout: timeout value in jiffies
@@ -1077,7 +1138,6 @@ static void process_timeout(unsigned lon
*/
fastcall signed long __sched schedule_timeout(signed long timeout)
{
- struct timer_list timer;
unsigned long expire;

switch (timeout)
@@ -1112,14 +1172,7 @@ fastcall signed long __sched schedule_ti

expire = timeout + jiffies;

- init_timer(&timer);
- timer.expires = expire;
- timer.data = (unsigned long) current;
- timer.function = process_timeout;
-
- add_timer(&timer);
- schedule();
- del_singleshot_timer_sync(&timer);
+ schedule_until(expire);

timeout = expire - jiffies;

-
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