Re: hdd kills vm

> Sent: Wednesday, November 01, 2023 at 10:06 AM > From: "Martin Kletzander" <mkletzan(a)redhat.com&gt; > To: "daggs" <daggs(a)gmx.com&gt; > Cc: users(a)lists.libvirt.org > Subject: Re: hdd kills vm > > On Tue, Oct 31, 2023 at 05:58:32PM +0100, daggs wrote: > >> Sent: Thursday, October 26, 2023 at 9:50 AM > >> From: "Martin Kletzander" <mkletzan(a)redhat.com&gt; > >> To: "daggs" <daggs(a)gmx.com&gt; > >> Cc: libvir-list(a)redhat.com > >> Subject: Re: hdd kills vm > >> > >> On Wed, Oct 25, 2023 at 03:06:55PM +0200, daggs wrote: > >> >> Sent: Tuesday, October 24, 2023 at 5:28 PM > >> >> From: "Martin Kletzander" <mkletzan(a)redhat.com&gt; > >> >> To: "daggs" <daggs(a)gmx.com&gt; > >> >> Cc: libvir-list(a)redhat.com > >> >> Subject: Re: hdd kills vm > >> >> > >> >> On Mon, Oct 23, 2023 at 04:59:08PM +0200, daggs wrote: > >> >> >Greetings Martin, > >> >> > > >> >> >> Sent: Sunday, October 22, 2023 at 12:37 PM > >> >> >> From: "Martin Kletzander" <mkletzan(a)redhat.com&gt; > >> >> >> To: "daggs" <daggs(a)gmx.com&gt; > >> >> >> Cc: libvir-list(a)redhat.com > >> >> >> Subject: Re: hdd kills vm > >> >> >> > >> >> >> On Fri, Oct 20, 2023 at 02:42:38PM +0200, daggs wrote: > >> >> >> >Greetings, > >> >> >> > > >> >> >> >I have a windows 11 vm running on my Gentoo using libvirt (9.8.0) + qemu (8.1.2), I'm passing almost all available resources to the vm > >> >> >> >(all 16 cpus, 31 out of 32 GB, nVidia gpu is pt), but the performance is not good, system lags, takes long time to boot. > >> >> >> > >> >> >> There are couple of things that stand out to me in your setup and I'll > >> >> >> assume the host has one NUMA node with 8 cores, each with 2 threads as, > >> >> >> just like you set it up in the guest XML. > >> >> >thats correct, see: > >> >> >$ lscpu | grep -i numa > >> >> >NUMA node(s): 1 > >> >> >NUMA node0 CPU(s): 0-15 > >> >> > > >> >> >however: > >> >> >$ dmesg | grep -i numa > >> >> >[ 0.003783] No NUMA configuration found > >> >> > > >> >> >can that be the reason? > >> >> > > >> >> > >> >> no, this is fine, 1 NUMA node is not a NUMA, technically, so that's > >> >> perfectly fine. > >> >thanks for clarifying it for me > >> > > >> >> > >> >> >> > >> >> >> * When you give the guest all the CPUs the host has there is nothing > >> >> >> left to run the host tasks. You might think that there "isn't > >> >> >> anything running", but there is, if only your init system, the kernel > >> >> >> and the QEMU which is emulating the guest. This is definitely one of > >> >> >> the bottlenecks. > >> >> >I've tried with 12 out of 16, same behavior. > >> >> > > >> >> >> > >> >> >> * The pinning of vCPUs to CPUs is half-suspicious. If you are trying to > >> >> >> make vCPU 0 and 1 be threads on the same core and on the host the > >> >> >> threads are represented as CPUs 0 and 8, then that's fine. If that is > >> >> >> just copy-pasted from somewhere, then it might not reflect the current > >> >> >> situation and can be source of many scheduling issues (even once the > >> >> >> above is dealt with). > >> >> >I found a site that does it for you, if it is wrong, can you point me to a place I can read about it? > >> >> > > >> >> > >> >> Just check what the topology is on the host and try to match it with the > >> >> guest one. If in doubt, then try it without the pinning. > >> >I can try to play with it, what I don't know is what should be the mapping logic? > >> > > >> > >> Threads on the same core in the guest should map to threads on the same > >> core in the host. Since there is no NUMA that should be enough to get > >> the best performance. But even misconfiguration of this will not > >> introduce lags in the system if it has 8 CPUs. So that's definitely not > >> the root cause of the main problem, it just might be suboptimal. > >> > >> >> > >> >> >> > >> >> >> * I also seem to recall that Windows had some issues with systems that > >> >> >> have too many cores. I'm not sure whether that was an issue with an > >> >> >> edition difference or just with some older versions, or if it just did > >> >> >> not show up in the task manager, but there was something that was > >> >> >> fixed by using either more sockets or cores in the topology. This is > >> >> >> probably not the issue for you though. > >> >> >> > >> >> >> >after trying a few ways to fix it, I've concluded that the issue might be related to the why the hdd is defined at the vm level. > >> >> >> >here is the xml: https://bpa.st/MYTA > >> >> >> >I assume that the hdd sits on the sata ctrl causing the issue but I'm not sure what is the proper way to fix it, any ideas? > >> >> >> > > >> >> >> > >> >> >> It looks like your disk is on SATA, but I don't see why that would be an > >> >> >> issue. Passing the block device to QEMU as VirtIO shouldn't cause that > >> >> >> much of a difference. Try measuring the speed of the disk on the host > >> >> >> and then in the VM maybe. Is that SSD or NVMe? I presume that's not > >> >> >> spinning rust, is it. > >> >> >as seen, I have 3 drives, 2 cdroms as sata and one hdd pt as virtio, I read somewhere that if the controller of the virtio > >> >> >device is sata, than it doesn't uses the virtio optimally. > >> >> > >> >> Well it _might_ be slightly more beneficial to use virtio-scsi or even > >> >> <disk type='block' device='lun'>, but I can't imagine that would make > >> >> the system lag. I'm not that familiar with the details. > >> >configure virtio-scsi and sata-scai at the same time? > >> > > >> > >> Yes, forgot that, sorry. Try virtio-scsi. You could also go farther > >> and pass through the LUN or the whole HBA (if you don't need to access > >> any other disk on it) to the VM. Try the information presented here: > >> > >> https://libvirt.org/formatdomain.html#usb-pci-scsi-devices > >> > >> >> > >> >> >it is a spindle, nvmes are too expensive where I live, frankly, I don't need lightning fast boot, the other BM machines running windows on spindle > >> >> >run it quite fast and they aren't half as fast as this server > >> >> > > >> >> > >> >> That might actually be related. The guest might think it is a different > >> >> type of disk and use completely suboptimal scheduling. This might > >> >> actually be solved by passing it as <disk device='lun'..., but at this > >> >> point I'm just guessing. > >> >I'll look into that, thanks. > > > >so bottom line, you suggest the following: > >1. remove the manual cpu pin, let qemu sort that out. > > You might try it, of course pinning it is in the end the better option. > > >2. add a virtio scsi controller and connect the os hdd to it > >3. pass the hss via scsi pt and not dev node > >4. if I able to do #3, no need to add device='lun' as it won't use the disk option > > > > First try (3), then you don't need to do anything else and if that > succeeds you have the superior configuration. If you can pass through > something that will not remove anything from your host system. > > >Dagg. > > > I've decided to first try #3 as yo suggested, based on this output: $ lsscsi [0:0:0:0] disk ATA WDC WD1003FZEX-0 1A01 /dev/sda [1:0:0:0] disk ATA WDC WD10EZEX-08W 1A02 /dev/sdb [2:0:0:0] disk ATA SAMSUNG HD103SJ 0001 /dev/sdc [3:0:0:0] disk ATA SAMSUNG HD103SJ 0001 /dev/sdd [4:0:0:0] disk ATA ST1000DM005 HD10 00E5 /dev/sde [5:0:0:0] disk ATA WDC WD10EZEX-08W 1A02 /dev/sdf [6:0:0:0] disk Kingston DataTraveler 3.0 0000 /dev/sdg [7:0:0:0] cd/dvd TS8XDVDS TRANSCEND 1.02 /dev/sr0 I deduced my data is 0:0:0:0, so I've added this to the file:

<controller type='scsi' index='0' model='virtio-scsi'> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/> </controller> <hostdev mode='subsystem' type='scsi' managed='no'>

<source> <adapter name='scsi_host0'/> <address bus='0' target='0' unit='0'/> </source> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </hostdev> removed the previous config and tried to boot, the vm didn't booted, the qemu log shows this: char device redirected to /dev/pts/0 (label charserial0) 2023-11-01T05:00:27.949977Z qemu-system-x86_64: vfio: Cannot reset device 0000:07:00.4, depends on group 16 which is not owned. 2023-11-01T05:00:28.113089Z qemu-system-x86_64: vfio: Cannot reset device 0000:07:00.4, depends on group 16 which is not owned. 2023-11-01T05:01:04.511969Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01T05:01:04.511993Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01T17:22:48.200982Z qemu-system-x86_64: libusb_release_interface: -4 [NO_DEVICE] 2023-11-01T17:22:48.201015Z qemu-system-x86_64: libusb_release_interface: -4 [NO_DEVICE] 2023-11-01T17:22:48.201025Z qemu-system-x86_64: libusb_release_interface: -4 [NO_DEVICE] 2023-11-01T17:22:48.201035Z qemu-system-x86_64: libusb_release_interface: -4 [NO_DEVICE] libusb_release_interface: -4 [NO_DEVICE] libusb_release_interface: -4 [NO_DEVICE] libusb_release_interface: -4 [NO_DEVICE] libusb_release_interface: -4 [NO_DEVICE] 2023-11-01T20:37:31.246043Z qemu-system-x86_64: vfio: Cannot reset device 0000:07:00.4, depends on group 16 which is not owned. 2023-11-01T20:37:31.465993Z qemu-system-x86_64: vfio: Cannot reset device 0000:07:00.4, depends on group 16 which is not owned. 2023-11-01T20:38:07.049875Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01T20:38:07.049910Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01T20:38:07.050063Z qemu-system-x86_64: libusb_set_interface_alt_setting: -99 [OTHER] 2023-11-01T20:47:47.400781Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01T20:47:47.400804Z qemu-system-x86_64: libusb_release_interface: -99 [OTHER] 2023-11-01 20:47:57.096+0000: shutting down, reason=shutdown 2023-11-01 20:57:37.514+0000: shutting down, reason=failed if I keep the scsi part but restore the previous device pt, it boots. any idea why it failed booting? Dagg.