> 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. > > Hi Vadim,
I have found that Bug 1013443 has been closed with a resolution of ERRATA. The windows device queue must be between 20 and 254 for StorPortSetDeviceQueueDepth to succeed. So I have the question that why queue_depth can not be set to pageNum(128)? Best wishes, Ting Wang >> >> How about using min(adaptExt->scsi_config.cmd_per_lun, pageNum) instead..? >> >> Thanks! >> >> -nab >> >>
