Hi Yan, So recently I've been doing some KVM guest performance comparisons between the scsi-mq prototype using virtio-scsi + vhost-scsi, and Windows Server 2012 with vioscsi.sys (virtio-win-0.1-74.iso) + vhost-scsi using PCIe flash backend devices.
I've noticed that small block random performance for the MSFT guest is at around ~80K IOPs with multiple vioscsi LUNs + adapters, which ends up being well below what the Linux guest with scsi-mq + virtio-scsi is capable of (~500K). After searching through the various vioscsi registry settings, it appears that MSIEnabled is being explicitly disabled (0x00000000), that is different from what vioscsi.inx is currently defining: [pnpsafe_pci_addreg_msix] HKR, "Interrupt Management",, 0x00000010 HKR, "Interrupt Management\MessageSignaledInterruptProperties",, 0x00000010 HKR, "Interrupt Management\MessageSignaledInterruptProperties", MSISupported, 0x00010001, 0 HKR, "Interrupt Management\MessageSignaledInterruptProperties", MessageNumberLimit, 0x00010001, 4 Looking deeper at vioscsi.c code, I've noticed that MSI_SUPPORTED=0 is explicitly disabled at build time in SOURCES + vioscsi.vcxproj, as well as VioScsiFindAdapter() code always ends setting msix_enabled = FALSE here, regardless of MSI_SUPPORTED: https://github.com/YanVugenfirer/kvm-guest-drivers-windows/blob/master/vioscsi/vioscsi.c#L340 Also looking at virtio_stor.c for the raw block driver, MSI_SUPPORTED=1 appears to be the default setting for the driver included in the offical virtio-win iso builds, right..? Sooo, I'd like to try enabling MSI_SUPPORTED=1 in a test vioscsi.sys build of my own, but before going down the WDK development rabbit whole, I'd like to better understand why you've explicitly disabled this logic within vioscsi.c code to start..? Is there anything that needs to be addressed / carried over from virtio_stor.c in order to get MSI_SUPPORTED=1 to work with vioscsi.c miniport code..? TIA! --nab
