Re: [libvirt] OpenStack/libvirt CAT interface

> > > > This translates to the following resctrltool-style reservations: > > > > res.vm-a.vcpu-2 > > > > type=both,size=VM-A-RESSIZE,cache-id=0 > > > > res.vm-b.vcpu-2 > > > > type=both,size=VM-B-RESSIZE,cache-id=0 > > > > Which translate to the following in resctrlfs: > > > > res.vm-a.vcpu-2 > > > > type=both,size=VM-A-RESSIZE,cache-id=0 > > type=both,size=default-size,cache-id=1 > > ... > > > > res.vm-b.vcpu-2 > > > > type=both,size=VM-B-RESSIZE,cache-id=0 > > type=both,size=default-size,cache-id=1 > > ... > >

> > Which is what we want, since the VCPUs are pinned. > > > > > > res.vm-a.vcpu-1 and res.vm-b.vcpu-1 don't need to > > be assigned to any reservation, which means they'll > > remain on the default group. > > You've showing type=both here which IIUC, means data > and instruction cache. No, type=both is non-cdp hosts (data and instructions reservations shared). type=data,type=code is for cdp hosts (data and instructions reservations separate). > Is that configuring one cache > that serves both purposes ? Yes. > Do we need to be able > to configure them independantly. Yes. > > RESTRICTIONS TO THE SYNTAX ABOVE > > ================================ > > > > Rules for the parameters: > > * type=code must be paired with type=data entry. > > What does this mean exactly when configuring guests ? Do > we have to configure data + instruction cache on the same > cache ID, do they have to be the same size, or are they > completely independant ? This means that a user can't specify this reservation: type=data,size=10mb,cache-id=1 They have to specify _both_ code and data sizes: type=data,size=10mb,cache-id=1; type=code,size=2mb,cache-id=1 Now a single both reservation is valid: type=both,size=10mb,cache-id=1

> > ABOUT THE LIST INTERFACE > > ======================== > > > > About an interface for listing the reservations > > of the system to OpenStack. > > > > I think that what OpenStack needs is to check, before > > starting a guest on a given host, that there is sufficient > > space available for the reservation. > > > > To do that, it can: > > > > 1) resctrltool list (the end of the output mentions > > how much free space available there is), or > > via resctrlfs directly (have to lock the filesystem, > > read each directory, AND each schemata, and count > > number of zero bits). > > 2) Via libvirt > > > > Should fix resctrltool/API to list amount of contiguous free space > > OpenStack, should just use libvirt APIs exclusively - there should not > be any need for it to use other tools if we've designed the libvirt API > correctly. Got it. -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list