On 20 January 2016 at 19:44, Christian Borntraeger <[email protected]> wrote: > 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. >
Thank you for the info. > 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? > In newer kernel config we have kvm module as a built in, rather than a module. I was thinking to move vm.allocate_pgste=1 from procps package (installed everywhere) to qemu package (installed when going to run VMs). -- Regards, Dimitri. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1533646 Title: Could you set vm.allocate_pgste = 1 by default? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1533646/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
