[Xenomai-core] [patch, minor] xnpipe_recv and xntimer_get_timeout_periodic()
[ resent. subject was broken ]
Hello,
[ pipe.c.patch ] update the timeout variable so that the
remaining timeout is used in case of consequent xnsynch_sleep_on()
calls.
As I understand that may indeed happen in case when another thread steals data while this one waits to be scheduled in.
[ timer.c.patch] xnticks_t is unsigned while (as I understand)
xntlholder_date(timer-plink) - nkpod-jiffies can be
negative.
In this case, some positive big number is returned and any code that
relies on xnthread_timeout() or xntimer_get_timeout() and runs over
periodic mode won't work properly (e.g. xnsynch_sleep_on() and
xnpipe_recv() now). Not sure 1 should be returned in this case (so far
I just did it the same way as xntimer_get_timeout_aperiodic()), I guess
0 would be better in both cases.
At least in theory, 1 may cause an (even) infinite loop in
xnpipe_recv() as I don't like a check for timeout 1 to be placed
there. It's something that should be decided at the timer layer - I
mean, whether it's too late to sleep or not.
hope, I haven't overlooked anything this time :o)
-- Best regards,Dmitry Adamushko
--- pipe-SVN.c 2006-08-20 15:04:25.0 +0200
+++ pipe.c 2006-08-20 21:29:55.0 +0200
@@ -450,6 +450,9 @@ ssize_t xnpipe_recv(int minor, struct xn
ret = -EIDRM;
goto unlock_and_exit;
}
+
+ /* remaining timeout */
+ timeout = xnthread_timeout(thread);
}
*pmh = link2mh(holder);
--- timer-SVN.c 2006-08-20 15:50:18.0 +0200
+++ timer.c 2006-08-20 15:54:30.0 +0200
@@ -313,7 +313,12 @@ static xnticks_t xntimer_get_date_period
static xnticks_t xntimer_get_timeout_periodic(xntimer_t *timer)
{
- return xntlholder_date(timer-plink) - nkpod-jiffies;
+ xnticks_t now = nkpod-jiffies;
+
+ if (xntlholder_date(timer-plink) now)
+ return 1; /* Will elapse shortly. */
+
+ return xntlholder_date(timer-plink) - now;
}
static xnticks_t xntimer_get_raw_expiry_periodic(xntimer_t *timer)
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Re: [Xenomai-core] [patch, minor] xnpipe_recv and xntimer_get_timeout_periodic()
On Mon, 2006-08-21 at 10:36 +0200, Dmitry Adamushko wrote: Not sure 1 should be returned in this case (so far I just did it the same way as xntimer_get_timeout_aperiodic()), I guess 0 would be better in both cases. Zero (XN_INFINITE) is reserved to indicate a non-running timer. -- Philippe. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] [patch, minor] xnpipe_recv and xntimer_get_timeout_periodic()
On Mon, 2006-08-21 at 10:36 +0200, Dmitry Adamushko wrote: [ timer.c.patch] xnticks_t is unsigned while (as I understand) xntlholder_date(timer-plink) - nkpod-jiffies can be negative. Well, normally, it should not. In periodic mode, each and every tick is processed by the timer handler which also maintains the time base (nkpod-jiffies), and as such, no timer should remain outstanding after its wakeup time has elapsed, otherwise, something is broken in the timer wheel management in the first place. IOW, we should never miss a tick, and consequently, negative timeouts cannot exist, since a timer is either running (= 0), or scheduled to elapse in the future ( 0). On the contrary, aperiodic mode is based on some free running TSC value not controlled by the nucleus, and as such, we might well ask for the timeout value slightly before the related timer elapses, and end up reading the TSC a bit later than its timeout date. -- Philippe. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] [patch, minor] xnpipe_recv and xntimer_get_timeout_periodic()
On Mon, 2006-08-21 at 12:47 +0200, Dmitry Adamushko wrote: what about pipe-related change (I mean timeslice updating in xnpipe_recv()) ? It's basically useless, since xnsynch_sleep_on() handles the resource stealing case internally, and the loop in xnpipe_recv is fake actually. Think of it as a goto statement in disguise. -- Best regards, Dmitry Adamushko -- Philippe. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] [patch, minor] xnpipe_recv and xntimer_get_timeout_periodic()
On Mon, 2006-08-21 at 19:45 +0200, Dmitry Adamushko wrote: On 21/08/06, Philippe Gerum [EMAIL PROTECTED] wrote: On Mon, 2006-08-21 at 10:36 +0200, Dmitry Adamushko wrote: [ timer.c.patch] xnticks_t is unsigned while (as I understand) xntlholder_date(timer-plink) - nkpod-jiffies can be negative. ok, I somehow missed a check for xntimer_running_p() in xntimer_get_timeout(). I bet it was not there when I was looking at this part of code yesterday or maybe I just had too much u wonderful belgium beer :o) It's been there since the fusion times! Ok, it must be the beer... :o Actually xntimer_get_timeout() should be called with nklock held + irq off as it must be atomic. But anyway, this is how it's used in all places and it's probably not supposed to be used as is from any upper layer. So it's ok. Indeed. -- Best regards, Dmitry Adamushko -- Philippe. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
