On Tue, 2014-02-18 at 13:11 -0800, Nicholas A. Bellinger wrote: > On Tue, 2014-02-18 at 13:00 -0800, Nicholas A. Bellinger wrote: > > On Mon, 2014-02-10 at 11:05 -0800, Nicholas A. Bellinger wrote: > > > > <SNIP> > > > > > > > > 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.. > > > > > > > Just a quick update on progress. > > > > I've been able to successfully build + load a unsigned vioscsi.sys > > driver on Server 2012 with WDK 8.0. > > > > Running with MSI_SUPPORTED=1 against vhost-scsi results in a significant > > performance and efficiency gain, on the order of 100K to 225K IOPs for > > 4K block random I/O workload, depending on read/write mix. > > > > One other performance related question.. > > In vioscsi.c:VioScsiFindAdapter() code, the default setting for > adaptExt->queue_depth ends up getting set to 32 (pageNum / 4) when > indirect mode is enabled in the following bits: > > if(adaptExt->indirect) { > adaptExt->queue_depth = max(2, (pageNum / 4)); > } else { > adaptExt->queue_depth = pageNum / ConfigInfo->NumberOfPhysicalBreaks - 1; > } > > Looking at viostor/virtio_stor.c:VirtIoFindAdapter() code, the default > setting for ->queue_depth appears to be 128 (pageNum): > > #if (INDIRECT_SUPPORTED) > if(!adaptExt->dump_mode) { > adaptExt->indirect = CHECKBIT(adaptExt->features, VIRTIO_RING_F_INDIRECT_DESC); > } > if(adaptExt->indirect) { > adaptExt->queue_depth = pageNum; > } > #else > adaptExt->indirect = 0; > #endif > > Is there a reason for the lower queue_depth for vioscsi vs. viostor..? It's a horrible work around for the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=1013443 I'm going to remove it as soon as found better solution for it. Best regards, Vadim. > > How about using min(adaptExt->scsi_config.cmd_per_lun, pageNum) instead..? > > Thanks! > > -nab > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
