Re: [libvirt-users] nvme, spdk and host linux version
On 12/12/19 3:51 PM, Mauricio Tavares wrote: On Thu, Dec 12, 2019 at 5:40 AM Michal Privoznik wrote: On 11/27/19 4:12 PM, Mauricio Tavares wrote: I have been following the patches on nvme support on the list and was wondering: If I wanted to build a vm host to be on the bleeding edge for nvme and spdk fun in libvirt, which linux distro -- fedora/ubuntu/centos/etc -- should I pick? For NVMe itself it probably doesn't matter as it doesn't require any special library. However, I'm not so sure about SPDK, esp. whether my NVMe patches is what you really need? My patches enable the only missing combination: host kernel storage stack + qemu storage stack = This has disadvantage of latency added by both stacks, but allows migration. neither host kernel nor qemu storage stack = (aka PCI assignment) This offers near bare metal latencies, but prohibits migration. qemu storage stack only = This is what my patches implement and should combine the above two: small latencies and ability to migrate. That is actually my question: is handing the hard drive through PCI assignment faster or slowe than disk type='nvme'? According to: https://www.linux-kvm.org/images/4/4c/Userspace_NVMe_driver_in_QEMU_-_Fam_Zheng.pdf (slide 25) the fastest is the host, followed by PCI assignment (in qemu it's called VFIO), then disk type='nvme' and the last one is disk type='block' with /dev/nvme0 (referred to as linux-aio). Michal ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
Re: [libvirt-users] nvme, spdk and host linux version
On Thu, Dec 12, 2019 at 5:40 AM Michal Privoznik wrote: > > On 11/27/19 4:12 PM, Mauricio Tavares wrote: > > I have been following the patches on nvme support on the list and was > > wondering: If I wanted to build a vm host to be on the bleeding edge > > for nvme and spdk fun in libvirt, which linux distro -- > > fedora/ubuntu/centos/etc -- should I pick? > > > > For NVMe itself it probably doesn't matter as it doesn't require any > special library. However, I'm not so sure about SPDK, esp. whether my > NVMe patches is what you really need? My patches enable the only missing > combination: > > host kernel storage stack + qemu storage stack = >This has disadvantage of latency added by both stacks, but allows > migration. > > neither host kernel nor qemu storage stack = (aka PCI assignment) >This offers near bare metal latencies, but prohibits migration. > > qemu storage stack only = >This is what my patches implement and should combine the above two: > small latencies and ability to migrate. > That is actually my question: is handing the hard drive through PCI assignment faster or slowe than disk type='nvme'? > > Michal > ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
Re: [libvirt-users] nvme, spdk and host linux version
On 11/27/19 4:12 PM, Mauricio Tavares wrote: I have been following the patches on nvme support on the list and was wondering: If I wanted to build a vm host to be on the bleeding edge for nvme and spdk fun in libvirt, which linux distro -- fedora/ubuntu/centos/etc -- should I pick? For NVMe itself it probably doesn't matter as it doesn't require any special library. However, I'm not so sure about SPDK, esp. whether my NVMe patches is what you really need? My patches enable the only missing combination: host kernel storage stack + qemu storage stack = This has disadvantage of latency added by both stacks, but allows migration. neither host kernel nor qemu storage stack = (aka PCI assignment) This offers near bare metal latencies, but prohibits migration. qemu storage stack only = This is what my patches implement and should combine the above two: small latencies and ability to migrate. Michal ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
Re: [libvirt-users] nvme, spdk and host linux version
On Tue, Dec 10, 2019 at 06:42:40PM -0500, Cole Robinson wrote: On 11/27/19 10:12 AM, Mauricio Tavares wrote: I have been following the patches on nvme support on the list and was wondering: If I wanted to build a vm host to be on the bleeding edge for nvme and spdk fun in libvirt, which linux distro -- fedora/ubuntu/centos/etc -- should I pick? IMO Fedora, most of libvirt is developed by @redhat people so there's plenty of Fedora expertise around Gentoo is also a popular choice among libvirt developers. Jano - Cole ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users signature.asc Description: PGP signature ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
Re: [libvirt-users] nvme, spdk and host linux version
On 11/27/19 10:12 AM, Mauricio Tavares wrote: > I have been following the patches on nvme support on the list and was > wondering: If I wanted to build a vm host to be on the bleeding edge > for nvme and spdk fun in libvirt, which linux distro -- > fedora/ubuntu/centos/etc -- should I pick? IMO Fedora, most of libvirt is developed by @redhat people so there's plenty of Fedora expertise around - Cole ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
[libvirt-users] nvme, spdk and host linux version
I have been following the patches on nvme support on the list and was wondering: If I wanted to build a vm host to be on the bleeding edge for nvme and spdk fun in libvirt, which linux distro -- fedora/ubuntu/centos/etc -- should I pick? ___ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
