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Re: [libvirt] [v5 0/9] Support cache tune in libvirt



On Mon, Feb 13, 2017 at 03:46:38PM +0800, Eli Qiao wrote:
> Addressed comment from v4 -> v5:
> 
> Marcelo:
>        * Several typos
>        * Use flock instead of virFileLock
> 
> 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
> 
>       * 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;...

Working as expected:

     <cachetune id='10' host_id='1' type='l3' size='2816' unit='KiB' vcpus='1' />

# cat schemata 
L3DATA:0=1;1=80000
L3CODE:0=1;1=80000

---

     <cachetune id='10' host_id='1' type='l3code' size='2816' unit='KiB'
vcpus='1' />
     <cachetune id='11' host_id='1' type='l3data' size='2816' unit='KiB'
vcpus='1' />

# cat schemata
L3DATA:0=1;1=40000
L3CODE:0=1;1=80000


Thanks.


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