Rob Bradford 0faa7afac2 vmm: Add fast path for PCI config IO port ... Looking up devices on the port I/O bus is time consuming during the boot at there is an O(lg n) tree lookup and the overhead from taking a lock on the bus contents. Avoid this by adding a fast path uses the hardcoded port address and size and directs PCI config requests directly to the device. Command line: target/release/cloud-hypervisor --kernel ~/src/linux/vmlinux --cmdline "root=/dev/vda1 console=ttyS0" --serial tty --console off --disk path=~/workloads/focal-server-cloudimg-amd64-custom-20210609-0.raw --api-socket /tmp/api PIO exit: 17913 PCI fast path: 17871 Percentage on fast path: 99.8% perf before: marvin:~/src/cloud-hypervisor (main *)$ perf report -g | grep resolve 6.20% 6.20% vcpu0 cloud-hypervisor [.] vm_device:🚌:Bus::resolve perf after: marvin:~/src/cloud-hypervisor (2021-09-17-ioapic-fast-path *)$ perf report -g | grep resolve 0.08% 0.08% vcpu0 cloud-hypervisor [.] vm_device:🚌:Bus::resolve The compromise required to implement this fast path is bringing the creation of the PciConfigIo device into the DeviceManager::new() so that it can be used in the VmmOps struct which is created before DeviceManager::create_devices() is called. Signed-off-by: Rob Bradford <robert.bradford@intel.com>		2021-09-17 17:09:45 +01:00
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src	vmm: Add fast path for PCI config IO port	2021-09-17 17:09:45 +01:00
Cargo.toml	build: bump vmm-sys-util from 0.8.0 to 0.9.0	2021-09-16 14:01:19 +01:00