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libqos: use microseconds instead of iterations for virtio timeout

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Some hosts are slow or overloaded so test execution takes a long time.
Test cases use timeouts to protect against an infinite loop stalling the
test forever (especially important in automated test setups).

Commit 6cd14054b6 ("libqos virtio:
Increase ISR timeout") increased the clock_step() value in an attempt to
lengthen the virtio interrupt wait timeout, but timeout failures are
still occuring on the Travis automated testing platform.

This is because clock_step() only affects the guest's virtual time.
Virtio requests can be bottlenecked on host disk I/O latency - which
cannot be improved by stepping the clock, so the fix was ineffective.

This patch changes the qvirtio_wait_queue_isr() and
qvirtio_wait_config_isr() timeout mechanism from loop iterations to
microseconds.  This way the test case can specify an absolute 30 second
timeout.  Number of loop iterations is not a reliable timeout mechanism
since the speed depends on many factors including host performance.

Tests should no longer timeout on overloaded Travis instances.

Cc: Marc Marí <marc.mari.barcelo@gmail.com>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Stefan Hajnoczi 2014-09-29 16:40:12 +01:00 • committed by Peter Maydell
parent e8c81b4d8a
commit 70556264a8
3 changed files with 42 additions and 43 deletions
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8
tests/libqos/virtio.h
View file

@ -160,15 +160,15 @@ void qvirtio_set_acknowledge(const QVirtioBus *bus, QVirtioDevice *d);
void qvirtio_set_driver(const QVirtioBus *bus, QVirtioDevice *d);
void qvirtio_set_driver_ok(const QVirtioBus *bus, QVirtioDevice *d);
bool qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
QVirtQueue *vq, uint64_t timeout);
void qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
QVirtQueue *vq, gint64 timeout_us);
uint8_t qvirtio_wait_status_byte_no_isr(const QVirtioBus *bus,
QVirtioDevice *d,
QVirtQueue *vq,
uint64_t addr,
gint64 timeout_us);
bool qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
uint64_t timeout);
void qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
gint64 timeout_us);
QVirtQueue *qvirtqueue_setup(const QVirtioBus *bus, QVirtioDevice *d,
QGuestAllocator *alloc, uint16_t index);