the TCG emulation of QEMU does work without allocatr_pgste. vm.allocate_pgste=1 is necessary to use the KVM kernel module (which is used by qemu in kvm mode)
The main difference is that this uses 4k page tables instead of 2k page tables on s390. So enabling pgstes will increase the page table overhead. The difference is usually pretty small, but might become noticeable when you have things like a big database with hundreds of processes accessing a big area of shared memory. Maybe something like # cat /etc/modprobe.d/99-kvm.conf install kvm /sbin/sysctl vm.allocate_pgste=1; /sbin/modprobe --ignore-install kvm remove kvm /sbin/sysctl vm.allocate_pgste=0; /sbin/modprobe -r --ignore-remove kvm would be good enough? -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1533646 Title: Could you set vm.allocate_pgste = 1 by default? Status in linux package in Ubuntu: Incomplete Bug description: Hello, to use qemu one needs vm.allocate_pgste = 1, on kernels that support that setting e.g. s390x. I'm now setting it with a sysctl.d snippet in procps package, however I was wondering if it could be set by default. Or not. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1533646/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
