Re: [libvirt] [v4 0/9] Support cache tune in libvirt

On Fri, Feb 10, 2017 at 02:42:04PM +0800, Eli Qiao wrote: > Addressed comment from v3 -> v4: > > Daniel & Marcelo: > * Added concurrence support > > Addressed comment from v2 -> v3: > > Daniel: > * Fixed coding style, passed `make check` and `make syntax-check` > > * Variables renaming and move from header file to c file. > > * For locking/mutex support, no progress. > > There are some discussion from mailing list, but I can not find a better > way to add locking support without performance impact. > > I'll explain the process and please help to advice what shoud we do. > > VM create: > 1) Get the cache left value on each bank of the host. This should be > shared amount all VMs. > 2) Calculate the schemata on the bank based on all created resctrl > domain's schemata > 3) Calculate the default schemata by scaning all domain's schemata. > 4) Flush default schemata to /sys/fs/resctrl/schemata > > VM destroy: > 1) Remove the resctrl domain of that VM > 2) Recalculate default schemata > 3) Flush default schemata to /sys/fs/resctrl/schemata > > The key point is that all VMs shares /sys/fs/resctrl/schemata, and > when a VM create a resctrl domain, the schemata of that VM depends on > the default schemata and all other exsited schematas. So a global > mutex is reqired. > > Before calculate a schemata or update default schemata, libvirt > should gain this global mutex. > > I will try to think more about how to support this gracefully in next > patch set. > > Marcelo: > * Added vcpu support for cachetune, this will allow user to define which > vcpu using which cache allocation bank. > > <cachetune id='0' host_id=0 size='3072' unit='KiB' vcpus='0,1'/> > > vcpus is a cpumap, the vcpu pids will be added to tasks file Working as expected. > * Added cdp compatible, user can specify l3 cache even host enable cdp. > See patch 8. > On a cdp enabled host, specify l3code/l3data by > > <cachetune id='0' host_id='0' type='l3' size='3072' unit='KiB'/> > > This will create a schemata like: > L3data:0=0xff00;... > L3code:0=0xff00;... > > * Would you please help to test if the functions work. Setting up CDP machine. Unrelated: Found a bug: The code should scan for all directories in resctrlfs, and then find free CBM space from that: free_cbm_space = ~(resctrldir1.CBM_bits & resctrldir2.CBM_bits & ... resctrldirN.CBM_bits) For all resctrlfs directories. The bug is as follows: Create a directory in resctrlfs by hand: # mkdir newres

# cd newres # echo "L3:0=3;1=f0000" > schemata # virsh start guest # cd ../b4c270b5-e0f9-4106-a446-69032872ed7e # cat schemata L3:0=3;1=f0000 That is, it is using the same CBM space as the "newres" reservation.