Re: [PATCH v4 0/5] enable Memory Bandwidth Monitoring (MBM) for VMs

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 20/01/15 09:45, Chao Peng wrote:
> Changes from v3:
> * Get timestamp information from host along with the monitoring counter;
>   This is required for counter overlow detection.
> * Address comments from Wei on the last patch.
>
> Changes from v2:
> * Remove the usage of "static" to cache data in xc;
>   NOTE: Other places that already existed before are not touched due to
>         the needs for API change. Will fix in separate patch if desirable.
> * Coding style;
>
> Changes from v1:
> * Move event type check from xc to xl;
> * Add retry capability for MBM sampling;
> * Fix Coding style/docs;
>
> Intel Memory Bandwidth Monitoring(MBM) is a new hardware feature
> which builds on the CMT infrastructure to allow monitoring of system
> memory bandwidth. Event codes are provided to monitor both "total"
> and "local" bandwidth, meaning bandwidth over QPI and other external
> links can be monitored.
>
> For XEN, MBM is used to monitor memory bandwidth for VMs. Due to its
> dependency on CMT, the software also makes use of most of CMT codes.
> Actually, besides introducing two additional events and some cpuid
> feature bits, there are no extra changes compared to cache occupancy
> monitoring in CMT. Due to this, CMT should be enabled first to use
> this feature.
>
> For interface changes, the patch serial introduces a new command
> "XEN_SYSCTL_PSR_CMT_get_l3_event_mask" which exposes MBM feature
> capability to user space and modified "resource_op" to support reading
> host timestamp.
> Tool stack side, two additional options introduced for "xl psr-cmt-show":
> total_mem_bandwidth:     Show total memory bandwidth
> local_mem_bandwidth:     Show local memory bandwidth
>
> The usage flow keeps the same with CMT.

Please, somewhere in this series (even if it is a solitary extra patch),
patch the command line documentation to add MBM next to the sentence
about CMT.

~Andrew

>
> Chao Peng (5):
>   x86: allow reading MSR_IA32_TSC with XENPF_resource_op
>   tools: add routine to get CMT L3 event mask
>   tools: correct coding style for psr
>   tools: code refactoring for MBM
>   tools: add total/local memory bandwith monitoring
>
>  docs/man/xl.pod.1                 |   9 +++
>  tools/libxc/include/xenctrl.h     |  14 ++--
>  tools/libxc/xc_msr_x86.h          |   1 +
>  tools/libxc/xc_psr.c              |  59 ++++++++++++---
>  tools/libxl/libxl.h               |  22 +++++-
>  tools/libxl/libxl_psr.c           | 155 ++++++++++++++++++++++++++++++++++----
>  tools/libxl/libxl_types.idl       |   2 +
>  tools/libxl/xl_cmdimpl.c          |  78 +++++++++++++------
>  tools/libxl/xl_cmdtable.c         |   4 +-
>  xen/arch/x86/platform_hypercall.c |   8 +-
>  10 files changed, 295 insertions(+), 57 deletions(-)
>