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Tsirkin" , Michal Privoznik , David Hildenbrand , qemu-devel@nongnu.org, Igor Mammedov , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" "Dr. David Alan Gilbert" writes: > * David Hildenbrand (david@redhat.com) wrote: >> We want to rate-limit MEMORY_DEVICE_SIZE_CHANGE events per device, >> otherwise we can lose some events for devices. As we might not always have >> a device id, add the qom-path to the event and use that to rate-limit >> per device. >> >> This was noticed by starting a VM with two virtio-mem devices that each >> have a requested size > 0. The Linux guest will initialize both devices >> in parallel, resulting in losing MEMORY_DEVICE_SIZE_CHANGE events for >> one of the devices. >> >> Fixes: 722a3c783ef4 ("virtio-pci: Send qapi events when the virtio-mem size changes") >> Suggested-by: Markus Armbruster >> Cc: "Dr. David Alan Gilbert" >> Cc: Markus Armbruster >> Cc: Michael S. Tsirkin >> Cc: Eric Blake >> Cc: Igor Mammedov >> Cc: Michal Privoznik >> Signed-off-by: David Hildenbrand >> --- >> >> Follow up of: >> https://lkml.kernel.org/r/20210921102434.24273-1-david@redhat.com >> >> v1 -> v2: >> - Add the qom-path and use that identifier to rate-limit per device >> - Rephrase subject/description >> >> --- >> hw/virtio/virtio-mem-pci.c | 3 ++- >> monitor/monitor.c | 9 +++++++++ >> qapi/machine.json | 5 ++++- >> 3 files changed, 15 insertions(+), 2 deletions(-) >> >> diff --git a/hw/virtio/virtio-mem-pci.c b/hw/virtio/virtio-mem-pci.c >> index fa5395cd88..dd5085497f 100644 >> --- a/hw/virtio/virtio-mem-pci.c >> +++ b/hw/virtio/virtio-mem-pci.c >> @@ -87,6 +87,7 @@ static void virtio_mem_pci_size_change_notify(Notifier *notifier, void *data) >> VirtIOMEMPCI *pci_mem = container_of(notifier, VirtIOMEMPCI, >> size_change_notifier); >> DeviceState *dev = DEVICE(pci_mem); >> + const char * qom_path = object_get_canonical_path(OBJECT(dev)); >> const uint64_t * const size_p = data; >> const char *id = NULL; >> >> @@ -94,7 +95,7 @@ static void virtio_mem_pci_size_change_notify(Notifier *notifier, void *data) >> id = g_strdup(dev->id); >> } >> >> - qapi_event_send_memory_device_size_change(!!id, id, *size_p); >> + qapi_event_send_memory_device_size_change(!!id, id, *size_p, qom_path); >> } >> >> static void virtio_mem_pci_class_init(ObjectClass *klass, void *data) >> diff --git a/monitor/monitor.c b/monitor/monitor.c >> index 46a171bca6..21c7a68758 100644 >> --- a/monitor/monitor.c >> +++ b/monitor/monitor.c >> @@ -474,6 +474,10 @@ static unsigned int qapi_event_throttle_hash(const void *key) >> hash += g_str_hash(qdict_get_str(evstate->data, "node-name")); >> } >> >> + if (evstate->event == QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE) { >> + hash += g_str_hash(qdict_get_str(evstate->data, "qom-path")); >> + } > > It makes me wonder if all these entries could turn into: > str = qdict_get_try_str(qdict, "qom-path"); > if (str) { > hash += g_str_hash(str); > } > > and then stop worrying about checking each eventtype there? Prone to accidental capture when we add to event data later on. I feel it's better to be explicit.