Daniel P. Berrangé, Sep 03, 2024 at 12:08: > On Mon, Sep 02, 2024 at 03:09:42PM +0200, Peter Krempa wrote: > > On Thu, Aug 22, 2024 at 17:59:47 +0200, Anthony Harivel wrote: > > > Add the support in libvirt to activate the RAPL feature in QEMU. > > I suppose that the 'rapl-helper-socket' is a shared (multiple qemu's use > > it) resource set up beforehand by the admin. Right? > > The qemu-pr-helper could be run as a single instnce, or it could be > run per-QEMU instance. The latter would give us better security > isolation, for what is a privileged daemon. On the other hand, I > wonder about the CPU overhead of having 100's of copies of the > process running on a host. > If it runs on a single instance, then the socket needs to be chmod/chown to something like qemu / libvirt group with access only to root and group. Running one helper instance per-QEMU instance would mean that every instance read 1 MSR / Package every second. The socket is left open (thanks to Daniel suggestion in QEMU review). The impact would be quite low I guess on the housekeeping CPU. When I designed the daemon with Paolo, the first solution was the main idea but I'm open to any solution that leads to a better adoption of the feature. Thanks, Anthony > > If that is the case that means the lifecycle of the daemon and > > permissions (including selinux) for accessing the socket are not > > something that libvirt needs to deal with. > > > > If either of them isn't true please outline how that socket is to be > > used to see how libvirt will need to approach it. > > > > With regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
