On 20/09/12 18:11, Gilles Chanteperdrix wrote: > On 09/19/2012 02:15 PM, Wolfgang Mauerer wrote: >> On 18/09/12 21:36, Gilles Chanteperdrix wrote: >>> On 09/18/2012 05:27 PM, Wolfgang Mauerer wrote:
>>> Ok. We have a currently pending issue on x86 which you should be >>> informed about before discovering it during your tests: using >>> rthal_supported_cpus is broken in I-pipe core patches when using the >>> LAPIC timer: since there is only one irq handler for all the LAPIC >>> timers, the handler is registered on all cpus, but on non started cpus, >>> the handler will do nothing at best, and not foward the LAPIC ticks to >>> Linux (which is still in control of the LAPIC timer on these cpus). >>> >>> This problem is due to the fact that we keep the same vector as Linux, >>> and so the same irq. There are two ways out of this: >>> >>> - change the LAPIC vector when xenomai takes the control of the LAPIC >>> timer, like we use to do, this is racy with current code because the >>> timer is taken by Xenomai but still used a bit by Linux, before it is >>> programmed by Xenomai, and Xenomai assumes that the host tick irq is the >>> same as the timer irq. All this can be fixed, but the last drawback of >>> this approach is that it does not fix the issue on architectures where >>> the local timer irq is the same on all cpus, but can not be changed, >>> hence the second approach; >>> - the second approach is to add a test at the beginning of >>> xnintr_clock_handler and forward the irq to the root domain if the >>> current cpu does not belong to xnarch_supported_cpus. This means some >>> patching of I-pipe timers so that ipipe_percpu.hrtimer_irq also gets >>> defined for non supported cpus when they use the timer shared with other >>> cpus, essentially what this patch tries (but fails) to achieve: >>> >>> http://www.xenomai.org/pipermail/xenomai/2012-September/026066.html >> >> thanks for the info! Unfortunately, I was not able to reproduce this >> issue quickly using two latency instances bound to different CPUs on a >> machine booted with isolcpus=1, though. > > The issue is not with isolcpus, but with rthal_supported_cpus, that is > xenomai "supported_cpus" parameter. And maybe Linux is running fine with > the bug, but if you do a cat /proc/interrupts, you should see the local > timer interrupt no longer incrementing on cpus not intercepted by xenomai. the attached patch (against core-4), which is a slight modification of yours, resolves the issue for me when applied together with the xnintr patch (I've also rebased to core-5, see https://github.com/siemens/ipipe core-3.5_for-upstream) Cheers, Wolfgang ######################################################################## Use ipipe_percpu.hrtimer_irq for non-RT CPUs when required We need to be able to forward the timer interrupt to the root domain on CPUs that are not used for real-time loads, but use a timer shared with other CPUs. Based on a patch by Gilles Chanteperdrix. Signed-off-by: Wolfgang Mauerer <wolfgang.maue...@siemens.com> --- kernel/ipipe/timer.c | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-) diff --git a/kernel/ipipe/timer.c b/kernel/ipipe/timer.c index 7dcd725..67ae4a7 100644 --- a/kernel/ipipe/timer.c +++ b/kernel/ipipe/timer.c @@ -172,11 +172,23 @@ int ipipe_select_timers(const struct cpumask *mask) hrclock_khz = tmp; spin_lock_irqsave(&lock, flags); - for_each_cpu(cpu, mask) { + for_each_cpu(cpu, cpu_online_mask) { list_for_each_entry(t, &timers, link) { if (!cpumask_test_cpu(cpu, t->cpumask)) continue; + /* + * When the CPU is not used for real-time + * loads, we need to be able to forward the + * IRQ for this CPU to the root domain in case + * it is shared with other CPUs. + */ + if (!cpumask_test_cpu(cpu, mask) + && t->irq == per_cpu(ipipe_percpu.hrtimer_irq, 0)) { + per_cpu(ipipe_percpu.hrtimer_irq, cpu) = t->irq; + goto found; + } + evtdev = t->host_timer; #ifdef CONFIG_GENERIC_CLOCKEVENTS if (!evtdev @@ -184,6 +196,9 @@ int ipipe_select_timers(const struct cpumask *mask) #endif /* CONFIG_GENERIC_CLOCKEVENTS */ goto found; } + if (!cpumask_test_cpu(cpu, mask)) + continue; + printk("I-pipe: could not find timer for cpu #%d\n", cpu); goto err_remove_all; -- 1.7.1 _______________________________________________ Xenomai mailing list Xenomai@xenomai.org http://www.xenomai.org/mailman/listinfo/xenomai
