Date: Tue, 23 Mar 2021 20:48:17 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 254513] virtio_random: random_harvestq spinning on a CPU with Q35 virtio random device Message-ID: <bug-254513-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254513 Bug ID: 254513 Summary: virtio_random: random_harvestq spinning on a CPU with Q35 virtio random device Product: Base System Version: 13.0-STABLE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: misc Assignee: bugs@FreeBSD.org Reporter: me@igalic.co This virtual machine is running @ Hetzner on their CPX series, which uses t= he Qemu Q35 chipset. Support for this has been recently added to FreeBSD and i= s in FreeBSD 13.0. The problem manifests as a load average of 1 on a 2 CPU system. `top -S` sh= ows: PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMM= AND 8 root 1 -16 - 0B 16K 0B CPU0 0 10:42 99.95% rand_harvestq So lets dig into the random device. The device is identified like this: grep -i entropy /var/run/dmesg.boot vtrnd0: <VirtIO Entropy Adapter> on virtio_pci4 random: registering fast source VirtIO Entropy Adapter meena@websrv2-hel1 ~> devinfo -p vtrnd0 -v vtrnd0 pnpinfo vendor=3D0x00001af4 device=3D0x1044 subvendor=3D0x1af4 device_type=3D0x00000004 virtio_pci4 pnpinfo vendor=3D0x1af4 device=3D0x1044 subvendor=3D0x1af4 subdevice=3D0x1100 class=3D0x00ff00 at slot=3D0 function=3D0 dbsf=3Dpci0:5:= 0:0 pci5 pcib5 pnpinfo vendor=3D0x1b36 device=3D0x000c subvendor=3D0x1b36 subdevice= =3D0x0000 class=3D0x060400 at slot=3D2 function=3D4 dbsf=3Dpci0:0:2:4=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 pci0 pcib0 pnpinfo _HID=3DPNP0A08 _UID=3D1 _CID=3DPNP0A03 at handle=3D\_SB_.PCI0 acpi0 nexus0 meena@websrv2-hel1 ~> procstat kstack on rand_harvestq process looks like this: 8 100097 rand_harvestq - vtrnd_read random_kthr= ead fork_exit fork_trampoline=20 suggesting this is virtio_related After adding devmatch_blacklist=3D"virtio_random.ko" to rc.conf, and rebooting, the CPU spinning issue goes away. --=20 You are receiving this mail because: You are the assignee for the bug.=
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