RE: [Xen-ia64-devel] [IPF-ia64] with Cset 10690, creating aVTImakexen0 hang

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Hi, SAKAI
Forget wrong analysis in early email,

In the phase of EFI boot, there are many IO operations, so dom0 is woken up by
VTIdomain in most time, while hlt_timer is still registered, this may cause more
timer interrupts injected to dom0 than before.

Hope following modification help
#define TIMER_SLOP (50*1000) /* ns */
      set_timer(&v->arch.hlt_timer, vcpu_get_next_timer_ns(v)+TIMER_SLOP );
      do_sched_op_compat(SCHEDOP_block, 0);
      stop_timer(&v->arch.hlt_timer);

Thanks,
Anthony


>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Xu, Anthony
>Sent: 2006?7?12? 21:13
>To: Atsushi SAKAI; Alex Williamson; Zhang, Xiantao
>Cc: Isaku Yamahata; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-ia64-devel] [IPF-ia64] with Cset 10690,creating aVTImakexen0
>hang
>
>>From: Atsushi SAKAI
>>Sent: 2006?7?12? 19:05
>>My primary motivation is correct display of xenmon.py and xentop in 
>>BVT/CREDIT.
>>(N.B. SEDF displayed as same as x86, but BVT/CREDIT are not)
>>If only domU emulation is applied, it is a half way from my motivation.
>>Is dom0 dispatch another home work?
>>
>
>I suspect the slowness is not due to dom0 being scheduled out, but due to
>hlt_timer
>didn't work as expected.
>           set_timer(&v->arch.hlt_timer, vcpu_get_next_timer_ns(v));
>           do_sched_op_compat(SCHEDOP_block, 0);
>There is a time window between set_timer and dom0 being scheduled out, and 
>psr.i
>is 1. So if hlt_timer fires before do_sched_op_compat being called, dom0 will
>not be woken up by hlt_timer, and there is no timer interrupt for dom0 until
>domo
>is woken up ,yes, dom0 can be woken up by other external interrupts, but not
>by
>timer interrupt. And since dom0 is involved in VTIdomain bootup, this may lead
>to slowness of VTIdomain bootup.
>
>Above is my analysis, there isn't any evidence.
>
>You can do experiment to check it.
>Change above code sequence as following, this may reduce the impact of time
>window.
>
>set_timer(&v->arch.hlt_timer,
>cycle_to_ns(local_cpu_data->itm_delta)+NOW());
>do_sched_op_compat(SCHEDOP_block, 0);
>
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