forked from luck/tmp_suning_uos_patched
da4ad88cab
The use of any sort of waitqueue (simple or regular) for
wait/waking vcpus has always been an overkill and semantically
wrong. Because this is per-vcpu (which is blocked) there is
only ever a single waiting vcpu, thus no need for any sort of
queue.
As such, make use of the rcuwait primitive, with the following
considerations:
- rcuwait already provides the proper barriers that serialize
concurrent waiter and waker.
- Task wakeup is done in rcu read critical region, with a
stable task pointer.
- Because there is no concurrency among waiters, we need
not worry about rcuwait_wait_event() calls corrupting
the wait->task. As a consequence, this saves the locking
done in swait when modifying the queue. This also applies
to per-vcore wait for powerpc kvm-hv.
The x86 tscdeadline_latency test mentioned in
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| .. | ||
| hyp | ||
| vgic | ||
| aarch32.c | ||
| arch_timer.c | ||
| arm.c | ||
| hypercalls.c | ||
| mmio.c | ||
| mmu.c | ||
| perf.c | ||
| pmu.c | ||
| psci.c | ||
| pvtime.c | ||
| trace.h | ||