* [Qemu-devel] [PATCH] libqos: use microseconds instead of iterations for virtio timeout
@ 2014-09-26 16:35 Stefan Hajnoczi
2014-09-29 11:25 ` Peter Maydell
0 siblings, 1 reply; 2+ messages in thread
From: Stefan Hajnoczi @ 2014-09-26 16:35 UTC (permalink / raw)
To: qemu-devel
Cc: Marc Marí, Peter Maydell, Andreas Faerber, Stefan Hajnoczi
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 6cd14054b67774cc58a51fca6660cfa1d3c08059 ("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.
Note that I dropped an assertion that waits for the full timeout
duration to assert that no interrupt was raised. I think this is not a
huge loss because it makes the test case non-deterministic (it cannot
really prove the no interrupt will ever be raised).
Cc: Marc Marí <marc.mari.barcelo@gmail.com>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
tests/libqos/virtio.c | 30 +++++++++++++++-------------
tests/libqos/virtio.h | 8 ++++----
tests/virtio-blk-test.c | 52 ++++++++++++++++++++++---------------------------
3 files changed, 43 insertions(+), 47 deletions(-)
diff --git a/tests/libqos/virtio.c b/tests/libqos/virtio.c
index 9b6de2c..0f6ffa4 100644
--- a/tests/libqos/virtio.c
+++ b/tests/libqos/virtio.c
@@ -78,30 +78,32 @@ void qvirtio_set_driver_ok(const QVirtioBus *bus, QVirtioDevice *d)
QVIRTIO_DRIVER_OK | QVIRTIO_DRIVER | QVIRTIO_ACKNOWLEDGE);
}
-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)
{
- do {
+ gint64 start_time = g_get_monotonic_time();
+
+ for (;;) {
clock_step(100);
if (bus->get_queue_isr_status(d, vq)) {
- break; /* It has ended */
+ return;
}
- } while (--timeout);
-
- return timeout != 0;
+ g_assert(g_get_monotonic_time() - start_time <= 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)
{
- do {
+ gint64 start_time = g_get_monotonic_time();
+
+ for (;;) {
clock_step(100);
if (bus->get_config_isr_status(d)) {
- break; /* It has ended */
+ return;
}
- } while (--timeout);
-
- return timeout != 0;
+ g_assert(g_get_monotonic_time() - start_time <= timeout_us);
+ }
}
void qvring_init(const QGuestAllocator *alloc, QVirtQueue *vq, uint64_t addr)
diff --git a/tests/libqos/virtio.h b/tests/libqos/virtio.h
index 70b3376..42a37dd 100644
--- a/tests/libqos/virtio.h
+++ b/tests/libqos/virtio.h
@@ -160,10 +160,10 @@ 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);
-bool qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
- uint64_t timeout);
+void qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
+ QVirtQueue *vq, gint64 timeout_us);
+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);
diff --git a/tests/virtio-blk-test.c b/tests/virtio-blk-test.c
index 588666c..41efea1 100644
--- a/tests/virtio-blk-test.c
+++ b/tests/virtio-blk-test.c
@@ -41,7 +41,7 @@
#define QVIRTIO_BLK_T_GET_ID 8
#define TEST_IMAGE_SIZE (64 * 1024 * 1024)
-#define QVIRTIO_BLK_TIMEOUT 100
+#define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000)
#define PCI_SLOT 0x04
#define PCI_FN 0x00
@@ -183,8 +183,8 @@ static void pci_basic(void)
qvirtqueue_add(&vqpci->vq, req_addr + 528, 1, true, false);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -205,8 +205,8 @@ static void pci_basic(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -233,8 +233,8 @@ static void pci_basic(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -256,8 +256,8 @@ static void pci_basic(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -329,8 +329,8 @@ static void pci_indirect(void)
free_head = qvirtqueue_add_indirect(&vqpci->vq, indirect);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -354,8 +354,8 @@ static void pci_indirect(void)
free_head = qvirtqueue_add_indirect(&vqpci->vq, indirect);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -396,8 +396,7 @@ static void pci_config(void)
qmp("{ 'execute': 'block_resize', 'arguments': { 'device': 'drive0', "
" 'size': %d } }", n_size);
- g_assert(qvirtio_wait_config_isr(&qvirtio_pci, &dev->vdev,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_config_isr(&qvirtio_pci, &dev->vdev, QVIRTIO_BLK_TIMEOUT_US);
capacity = qvirtio_config_readq(&qvirtio_pci, &dev->vdev, addr);
g_assert_cmpint(capacity, ==, n_size / 512);
@@ -452,8 +451,7 @@ static void pci_msix(void)
qmp("{ 'execute': 'block_resize', 'arguments': { 'device': 'drive0', "
" 'size': %d } }", n_size);
- g_assert(qvirtio_wait_config_isr(&qvirtio_pci, &dev->vdev,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_config_isr(&qvirtio_pci, &dev->vdev, QVIRTIO_BLK_TIMEOUT_US);
capacity = qvirtio_config_readq(&qvirtio_pci, &dev->vdev, addr);
g_assert_cmpint(capacity, ==, n_size / 512);
@@ -473,8 +471,8 @@ static void pci_msix(void)
qvirtqueue_add(&vqpci->vq, req_addr + 528, 1, true, false);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -497,8 +495,8 @@ static void pci_msix(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -574,8 +572,8 @@ static void pci_idx(void)
qvirtqueue_add(&vqpci->vq, req_addr + 528, 1, true, false);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
/* Write request */
req.type = QVIRTIO_BLK_T_OUT;
@@ -594,10 +592,6 @@ static void pci_idx(void)
qvirtqueue_add(&vqpci->vq, req_addr + 528, 1, true, false);
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- /* No notification expected */
- g_assert(!qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
-
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
@@ -619,8 +613,8 @@ static void pci_idx(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
- g_assert(qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
- QVIRTIO_BLK_TIMEOUT));
+ qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
+ QVIRTIO_BLK_TIMEOUT_US);
status = readb(req_addr + 528);
g_assert_cmpint(status, ==, 0);
--
1.9.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH] libqos: use microseconds instead of iterations for virtio timeout
2014-09-26 16:35 [Qemu-devel] [PATCH] libqos: use microseconds instead of iterations for virtio timeout Stefan Hajnoczi
@ 2014-09-29 11:25 ` Peter Maydell
0 siblings, 0 replies; 2+ messages in thread
From: Peter Maydell @ 2014-09-29 11:25 UTC (permalink / raw)
To: Stefan Hajnoczi; +Cc: Marc Marí, QEMU Developers, Andreas Faerber
On 26 September 2014 17:35, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> 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 6cd14054b67774cc58a51fca6660cfa1d3c08059 ("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.
>
> Note that I dropped an assertion that waits for the full timeout
> duration to assert that no interrupt was raised. I think this is not a
> huge loss because it makes the test case non-deterministic (it cannot
> really prove the no interrupt will ever be raised).
As per IRC conversation, this patch causes 'make check'
to fail on some (slower?) systems with:
ERROR:/home/petmay01/linaro/qemu-for-merges/tests/virtio-blk-test.c:596:pci_idx:
assertion failed (status == 0): (255 == 0)
Stefan has diagnosed this as a failure to poll for the
zero status code, and is working on a patch.
-- PMM
^ permalink raw reply [flat|nested] 2+ messages in thread
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