After all the previous refactoring patches, we can finally create
multiple threads under the same backend. This is directly combined with
multiqueues so that it will create one thread per queue.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Anticipating the follow up patches to run multiple threads for the same
backend, we need the initialization of the disk to happen in the high
level structure VhostUserBlkBackend.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The DiskFile will need to be shared across multiple threads when running
multiple queues across these threads. That's why it needs to be put
inside an Arc. The reason for the Mutex is because execute() expects a
mutable object implementing Read + Write + Seek. Unfortunately, this
create a contention point as the object needs to be locked from each
thread, reducing the performance gain we will get with multiple threads.
The need for an immutable object would solve this problem, and it will
be addressed later through follow up patches.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
There is no need for retrieving the VringWorker since we don't need to
register some extra file descriptors to the epoll loop.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By adding a "thread_id" parameter to handle_event(), the backend crate
can now indicate to the backend implementation which thread triggered
the processing of some events.
This is applied to vhost-user-net backend and allows for simplifying a
lot the code since each thread is identical.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By adding the "thread_index" parameter to the function exit_event() from
the VhostUserBackend trait, the backend crate now has the ability to ask
the backend implementation about the exit event related to a specific
thread.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that multiple worker threads can be run from the backend crate, it
is important that each backend implementation can access every worker
thread.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By changing the mutability of this function, after adapting all
backends, we should be able to implement multithreads with
multiqueues support without hitting a bottleneck on the backend
locking.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Both blk, net and fs backends have been updated to avoid the requirement
of having handle_event(&mut self). This will allow the backend crate to
avoid taking a write lock onto the backend object, which will remove the
potential contention point when multiple threads will be handling
multiqueues.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This change, combined with the compiler hint to inline get_used_event,
shortens the window between the memory read and the actual check by
calling get_used_event from needs_notification.
Without it, when putting enough pressure on the vring, it's possible
that a notification is wrongly omitted, causing the queue to stall.
Signed-off-by: Sergio Lopez <slp@redhat.com>
As cloud-hypervisor/vhost crate (dragonball branch) is ready to be used,
switch vhost_rs from internal crate to the external one.
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
Now that vhost_user_backend and vm-virtio do support EVENT_IDX, use it
in vhost_user_block to reduce the number of notifications sent between
the driver and the device.
This is specially useful when using active polling on the virtqueue,
as it'll be implemented by a future patch.
This is a snapshot of kvm_stat while generating ~60K IOPS with fio on
the guest without EVENT_IDX:
Event Total %Total CurAvg/s
kvm_entry 393454 20.3 62494
kvm_exit 393446 20.3 62494
kvm_apic_accept_irq 378146 19.5 60268
kvm_msi_set_irq 369720 19.0 58881
kvm_fast_mmio 370497 19.1 58817
kvm_hv_timer_state 10197 0.5 1715
kvm_msr 8770 0.5 1443
kvm_wait_lapic_expire 7018 0.4 1118
kvm_apic 2768 0.1 538
kvm_pv_tlb_flush 2028 0.1 360
kvm_vcpu_wakeup 1453 0.1 278
kvm_apic_ipi 1384 0.1 269
kvm_fpu 1148 0.1 164
kvm_pio 574 0.0 82
kvm_userspace_exit 574 0.0 82
kvm_halt_poll_ns 24 0.0 3
And this is the snapshot while doing the same thing with EVENT_IDX:
Event Total %Total CurAvg/s
kvm_entry 35506 26.0 3873
kvm_exit 35499 26.0 3873
kvm_hv_timer_state 14740 10.8 1672
kvm_apic_accept_irq 13017 9.5 1438
kvm_msr 12845 9.4 1421
kvm_wait_lapic_expire 10422 7.6 1118
kvm_apic 3788 2.8 502
kvm_pv_tlb_flush 2708 2.0 340
kvm_vcpu_wakeup 1992 1.5 258
kvm_apic_ipi 1894 1.4 251
kvm_fpu 1476 1.1 164
kvm_pio 738 0.5 82
kvm_userspace_exit 738 0.5 82
kvm_msi_set_irq 701 0.5 69
kvm_fast_mmio 238 0.2 4
kvm_halt_poll_ns 50 0.0 1
kvm_ple_window_update 28 0.0 0
kvm_page_fault 4 0.0 0
It can be clearly appreciated how the number of vm exits per second,
specially the ones related to notifications (kvm_fast_mmio and
kvm_msi_set_irq) is drastically lower.
Signed-off-by: Sergio Lopez <slp@redhat.com>
Add helpers to Vring and VhostUserSlaveReqHandler for EVENT_IDX, so
consumers of this crate can make use of this feature.
Signed-off-by: Sergio Lopez <slp@redhat.com>
Implement the newly added exit_event() method on the VhostUserBackend
trait to allow the backend to provide an EventFD for triggering an exit
of the worker thread.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Adding the num_queues parameter for vhost-user-blk backend, which
can enable MQ support in the backend.
This patch has enabled the MQ support from handle_event, and the
vhost-user-backend crate will enable multiple threads to call this
handle_event to handle read/write operations.
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Split the basic launching functionality into its own function in the
newly added vhost_user_block crate.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Extract the majority of the code that provides the vhost-user-block
backend into its own crate and port the binary to use it.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
