On Tue, 22 Dec 2020 22:26:45 +0100 Zdenek Kaspar <zkaspar82@xxxxxxxxx> wrote: > On Tue, 22 Dec 2020 09:07:39 -0800 > Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > On Mon, Dec 21, 2020, Zdenek Kaspar wrote: > > > [ 179.364305] WARNING: CPU: 0 PID: 369 at > > > kvm_mmu_zap_oldest_mmu_pages+0xd1/0xe0 [kvm] [ 179.365415] Call > > > Trace: [ 179.365443] paging64_page_fault+0x244/0x8e0 [kvm] > > > > This means the shadow page zapping is occuring because KVM is > > hitting the max number of allowed MMU shadow pages. Can you > > provide your QEMU command line? I can reproduce the performance > > degredation, but only by deliberately overriding the max number of > > MMU pages via `-machine kvm-shadow-mem` to be an absurdly low value. > > > > > [ 179.365596] kvm_mmu_page_fault+0x376/0x550 [kvm] > > > [ 179.365725] kvm_arch_vcpu_ioctl_run+0xbaf/0x18f0 [kvm] > > > [ 179.365772] kvm_vcpu_ioctl+0x203/0x520 [kvm] > > > [ 179.365938] __x64_sys_ioctl+0x338/0x720 > > > [ 179.365992] do_syscall_64+0x33/0x40 > > > [ 179.366013] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > It's one long line, added "\" for mail readability: > > qemu-system-x86_64 -machine type=q35,accel=kvm \ > -cpu host,host-cache-info=on -smp cpus=2,cores=2 \ > -m size=1024 -global virtio-pci.disable-legacy=on \ > -global virtio-pci.disable-modern=off \ > -device virtio-balloon \ > -device virtio-net,netdev=tap-build,mac=DE:AD:BE:EF:00:80 \ > -object rng-random,filename=/dev/urandom,id=rng0 \ > -device virtio-rng,rng=rng0 \ > -name build,process=qemu-build \ > -drive > file=/mnt/data/export/unix/kvm/build/openbsd-amd64.img,if=virtio,cache=none,format=raw,aio=native > \ -netdev type=tap,id=tap-build,vhost=on \ -serial > none \ -parallel none > \ -monitor > unix:/dev/shm/kvm-build.sock,server,nowait \ -enable-kvm > -daemonize -runas qemu > > Z. BTW, v5.11-rc3 with kvm-shadow-mem=1073741824 it seems OK. Just curious what v5.8 does, so by any chance is there command for kvm-shadow-mem value via qemu monitor? Z.
