Hi Vadim & Yan, On Sun, 2014-02-09 at 22:35 +1100, Vadim Rozenfeld wrote: > On Sun, 2014-02-09 at 11:24 +0200, Yan Vugenfirer wrote: > > Hi Nicholas, > > > > Adding Vadim Rozenfeld who wrote the virtio-scsi driver. > > > > Best regards, > > Yan. > > > > On Feb 7, 2014, at 10:14 PM, Nicholas A. Bellinger <n...@linux-iscsi.org> > > wrote: > > > > > 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..? > > Hi Nicholas, > > I was thinking about enabling MSI in RHEL 6.6 (build 74) but for some > reasons decided to keep it disabled until adding mq support. > > > You definitely should be able to turn on MSI_SUPPORTED, rebuild the > driver, and switch MSISupported to 1 to make vioscsi driver working in > MSI mode. >
Thanks for the quick response. We'll give MSI_SUPPORTED=1 a shot over the next days with a test build on Server 2012 / Server 2008 R2 and see how things go.. Thanks again! --nab
