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SubjectRe: -rt doesn't compile for UML

* Miklos Szeredi <miklos@szeredi.hu> wrote:

> > it doesnt need it - turn IRQOFF_TRACING off.
>
> # CONFIG_CRITICAL_IRQSOFF_TIMING is not set
>
> This seems to be off.
>
> But latency_trace.c uses irqs_disabled_flags(), which is defined in
> <linux/irqflags.h> only if CONFIG_TRACE_IRQFLAGS_SUPPORT is set.
>
> So perhaps latency_trace.c should be using raw_irqs_disabled_flags()
> instead. But UML doesn't define that either and I have no idea how to
> do that, so this is still not solved yet.

irqs_disabled_flags() gives us a nonessential bit of the trace output:

_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
privoxy-12926 1.Ns1 0us : ktime_get_ts (ktime_get)
privoxy-12926 1.Ns1 0us : getnstimeofday (ktime_get_ts)
privoxy-12926 1.Ns1 1us : set_normalized_timespec (ktime_get_ts)
privoxy-12926 1.Ns1 1us : rb_first (htb_dequeue)

it's the 'irqs-off' flag, which is 'd', 'D' or '.'.

so you can define irqs_off_flags to always-0 and you should be able to
get pretty good traces still. It should have no functional impact.

Ingo
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