[PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[Chao Peng]

Changes from v8:
* Merge event mask patch to MBM enabling patch;
* Address comments from Ian Campbell(Detail in patch itself).

Changes from v7:
* Make obfuscating more complex as Jan suggested.
* Minor adjustment for commit message.

Changes from v6:
* Obfuscate the read value of MSR_IA32_TSC by adding a booting random;
* Minor coding style/comments adjustment;

Changes from v5:
* Remove common IRQ disable flag but instead disable IRQ when other MSR
  read followed by MSR_IA32_TSC read;
* Add comments for special handle for MSR_IA32_TSC;

Changes from v4:
* Make the counter read and timestamp read atomic by disable IRQ;
* Treat MSR_IA32_TSC as a special case and return NOW() for read path;
* Add MBM description in xl command line.

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 system time together with the monitored counter.

On the 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.
Chao Peng (3):
  tools: correct coding style for psr
  tools: code refactoring for MBM
  tools, docs: add total/local memory bandwith monitoring

 docs/man/xl.pod.1                   |  11 +++-
 docs/misc/xen-command-line.markdown |   3 +
 tools/libxc/include/xenctrl.h       |  14 +++--
 tools/libxc/xc_msr_x86.h            |   1 +
 tools/libxc/xc_psr.c                |  76 +++++++++++++++++------
 tools/libxl/libxl.h                 |  28 +++++++--
 tools/libxl/libxl_psr.c             |  81 +++++++++++++++++++++----
 tools/libxl/libxl_types.idl         |   2 +
 tools/libxl/xl_cmdimpl.c            | 118 ++++++++++++++++++++++++++++++------
 tools/libxl/xl_cmdtable.c           |   4 +-
 10 files changed, 280 insertions(+), 58 deletions(-)

-- 
1.9.1

[PATCH v9 1/3] tools: correct coding style for psr

[Chao Peng]

- space: remove space after '(' or before ')' in 'if' condition;
- indention: align function definition/call arguments;

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
---
 tools/libxc/include/xenctrl.h | 10 +++++-----
 tools/libxc/xc_psr.c          | 10 +++++-----
 tools/libxl/libxl.h           | 11 +++++++----
 tools/libxl/libxl_psr.c       | 11 +++++++----
 tools/libxl/xl_cmdimpl.c      | 11 ++++++-----
 5 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 0ad8b8d..c62f371 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2693,14 +2693,14 @@ typedef enum xc_psr_cmt_type xc_psr_cmt_type;
 int xc_psr_cmt_attach(xc_interface *xch, uint32_t domid);
 int xc_psr_cmt_detach(xc_interface *xch, uint32_t domid);
 int xc_psr_cmt_get_domain_rmid(xc_interface *xch, uint32_t domid,
-    uint32_t *rmid);
+                               uint32_t *rmid);
 int xc_psr_cmt_get_total_rmid(xc_interface *xch, uint32_t *total_rmid);
 int xc_psr_cmt_get_l3_upscaling_factor(xc_interface *xch,
-    uint32_t *upscaling_factor);
+                                       uint32_t *upscaling_factor);
 int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
-    uint32_t *l3_cache_size);
-int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid,
-    uint32_t cpu, uint32_t psr_cmt_type, uint64_t *monitor_data);
+                                 uint32_t *l3_cache_size);
+int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid, uint32_t cpu,
+                        uint32_t psr_cmt_type, uint64_t *monitor_data);
 int xc_psr_cmt_enabled(xc_interface *xch);
 #endif
 
diff --git a/tools/libxc/xc_psr.c b/tools/libxc/xc_psr.c
index 872e6dc..cfae172 100644
--- a/tools/libxc/xc_psr.c
+++ b/tools/libxc/xc_psr.c
@@ -47,7 +47,7 @@ int xc_psr_cmt_detach(xc_interface *xch, uint32_t domid)
 }
 
 int xc_psr_cmt_get_domain_rmid(xc_interface *xch, uint32_t domid,
-                                    uint32_t *rmid)
+                               uint32_t *rmid)
 {
     int rc;
     DECLARE_DOMCTL;
@@ -88,7 +88,7 @@ int xc_psr_cmt_get_total_rmid(xc_interface *xch, uint32_t *total_rmid)
 }
 
 int xc_psr_cmt_get_l3_upscaling_factor(xc_interface *xch,
-                                            uint32_t *upscaling_factor)
+                                       uint32_t *upscaling_factor)
 {
     static int val = 0;
     int rc;
@@ -113,7 +113,7 @@ int xc_psr_cmt_get_l3_upscaling_factor(xc_interface *xch,
 }
 
 int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
-                                      uint32_t *l3_cache_size)
+                                 uint32_t *l3_cache_size)
 {
     static int val = 0;
     int rc;
@@ -138,8 +138,8 @@ int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
     return rc;
 }
 
-int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid,
-    uint32_t cpu, xc_psr_cmt_type type, uint64_t *monitor_data)
+int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid, uint32_t cpu,
+                        xc_psr_cmt_type type, uint64_t *monitor_data)
 {
     xc_resource_op_t op;
     xc_resource_entry_t entries[2];
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 0a123f1..28b6325 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1454,10 +1454,13 @@ int libxl_psr_cmt_detach(libxl_ctx *ctx, uint32_t domid);
 int libxl_psr_cmt_domain_attached(libxl_ctx *ctx, uint32_t domid);
 int libxl_psr_cmt_enabled(libxl_ctx *ctx);
 int libxl_psr_cmt_get_total_rmid(libxl_ctx *ctx, uint32_t *total_rmid);
-int libxl_psr_cmt_get_l3_cache_size(libxl_ctx *ctx, uint32_t socketid,
-    uint32_t *l3_cache_size);
-int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx, uint32_t domid,
-    uint32_t socketid, uint32_t *l3_cache_occupancy);
+int libxl_psr_cmt_get_l3_cache_size(libxl_ctx *ctx,
+                                    uint32_t socketid,
+                                    uint32_t *l3_cache_size);
+int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
+                                      uint32_t domid,
+                                      uint32_t socketid,
+                                      uint32_t *l3_cache_occupancy);
 #endif
 
 /* misc */
diff --git a/tools/libxl/libxl_psr.c b/tools/libxl/libxl_psr.c
index 0437465..ec3b6e9 100644
--- a/tools/libxl/libxl_psr.c
+++ b/tools/libxl/libxl_psr.c
@@ -135,8 +135,9 @@ int libxl_psr_cmt_get_total_rmid(libxl_ctx *ctx, uint32_t *total_rmid)
     return rc;
 }
 
-int libxl_psr_cmt_get_l3_cache_size(libxl_ctx *ctx, uint32_t socketid,
-                                         uint32_t *l3_cache_size)
+int libxl_psr_cmt_get_l3_cache_size(libxl_ctx *ctx,
+                                    uint32_t socketid,
+                                    uint32_t *l3_cache_size)
 {
     GC_INIT(ctx);
 
@@ -160,8 +161,10 @@ out:
     return rc;
 }
 
-int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx, uint32_t domid,
-    uint32_t socketid, uint32_t *l3_cache_occupancy)
+int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
+                                      uint32_t domid,
+                                      uint32_t socketid,
+                                      uint32_t *l3_cache_occupancy)
 {
     GC_INIT(ctx);
 
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 0b02a6c..8fce979 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -7808,7 +7808,7 @@ out:
 
 #ifdef LIBXL_HAVE_PSR_CMT
 static void psr_cmt_print_domain_cache_occupancy(libxl_dominfo *dominfo,
-                                                    uint32_t nr_sockets)
+                                                 uint32_t nr_sockets)
 {
     char *domain_name;
     uint32_t socketid;
@@ -7822,8 +7822,8 @@ static void psr_cmt_print_domain_cache_occupancy(libxl_dominfo *dominfo,
     free(domain_name);
 
     for (socketid = 0; socketid < nr_sockets; socketid++) {
-        if ( !libxl_psr_cmt_get_cache_occupancy(ctx, dominfo->domid,
-                 socketid, &l3_cache_occupancy) )
+        if (!libxl_psr_cmt_get_cache_occupancy(ctx, dominfo->domid, socketid,
+                                               &l3_cache_occupancy))
             printf("%13u KB", l3_cache_occupancy);
     }
 
@@ -7871,8 +7871,9 @@ static int psr_cmt_show_cache_occupancy(uint32_t domid)
     for (socketid = 0; socketid < nr_sockets; socketid++) {
         rc = libxl_psr_cmt_get_l3_cache_size(ctx, socketid, &l3_cache_size);
         if (rc < 0) {
-            fprintf(stderr, "Failed to get system l3 cache size for socket:%d\n",
-                            socketid);
+            fprintf(stderr,
+                    "Failed to get system l3 cache size for socket:%d\n",
+                    socketid);
             return -1;
         }
         printf("%13u KB", l3_cache_size);
-- 
1.9.1

[PATCH v9 2/3] tools: code refactoring for MBM

[Chao Peng]

Make some internal routines common so that total/local memory bandwidth
monitoring in the next patch can make use of them.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
---
 tools/libxl/libxl_psr.c  | 44 +++++++++++++++++++++++++++------------
 tools/libxl/xl_cmdimpl.c | 54 +++++++++++++++++++++++++++++-------------------
 2 files changed, 64 insertions(+), 34 deletions(-)

diff --git a/tools/libxl/libxl_psr.c b/tools/libxl/libxl_psr.c
index ec3b6e9..1e1f7ee 100644
--- a/tools/libxl/libxl_psr.c
+++ b/tools/libxl/libxl_psr.c
@@ -161,20 +161,18 @@ out:
     return rc;
 }
 
-int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
-                                      uint32_t domid,
-                                      uint32_t socketid,
-                                      uint32_t *l3_cache_occupancy)
+static int libxl__psr_cmt_get_l3_monitoring_data(libxl__gc *gc,
+                                                 uint32_t domid,
+                                                 xc_psr_cmt_type type,
+                                                 uint32_t socketid,
+                                                 uint64_t *data_r)
 {
-    GC_INIT(ctx);
-
     unsigned int rmid;
     uint32_t upscaling_factor;
     uint64_t monitor_data;
     int cpu, rc;
-    xc_psr_cmt_type type;
 
-    rc = xc_psr_cmt_get_domain_rmid(ctx->xch, domid, &rmid);
+    rc = xc_psr_cmt_get_domain_rmid(CTX->xch, domid, &rmid);
     if (rc < 0 || rmid == 0) {
         LOGE(ERROR, "fail to get the domain rmid, "
             "or domain is not attached with platform QoS monitoring service");
@@ -189,23 +187,43 @@ int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
         goto out;
     }
 
-    type = XC_PSR_CMT_L3_OCCUPANCY;
-    rc = xc_psr_cmt_get_data(ctx->xch, rmid, cpu, type, &monitor_data);
+    rc = xc_psr_cmt_get_data(CTX->xch, rmid, cpu, type, &monitor_data);
     if (rc < 0) {
         LOGE(ERROR, "failed to get monitoring data");
         rc = ERROR_FAIL;
         goto out;
     }
 
-    rc = xc_psr_cmt_get_l3_upscaling_factor(ctx->xch, &upscaling_factor);
+    rc = xc_psr_cmt_get_l3_upscaling_factor(CTX->xch, &upscaling_factor);
     if (rc < 0) {
         LOGE(ERROR, "failed to get L3 upscaling factor");
         rc = ERROR_FAIL;
         goto out;
     }
 
-    *l3_cache_occupancy = upscaling_factor * monitor_data / 1024;
-    rc = 0;
+    *data_r = monitor_data * upscaling_factor;
+
+out:
+    return rc;
+}
+
+int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
+                                      uint32_t domid,
+                                      uint32_t socketid,
+                                      uint32_t *l3_cache_occupancy)
+{
+    GC_INIT(ctx);
+    uint64_t data;
+    int rc;
+
+    rc = libxl__psr_cmt_get_l3_monitoring_data(gc, domid,
+                                               XC_PSR_CMT_L3_OCCUPANCY,
+                                               socketid, &data);
+    if (rc < 0)
+            goto out;
+
+    *l3_cache_occupancy = data / 1024;
+
 out:
     GC_FREE;
     return rc;
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 8fce979..a0b50e7 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -7807,8 +7807,9 @@ out:
 }
 
 #ifdef LIBXL_HAVE_PSR_CMT
-static void psr_cmt_print_domain_cache_occupancy(libxl_dominfo *dominfo,
-                                                 uint32_t nr_sockets)
+static void psr_cmt_print_domain_l3_info(libxl_dominfo *dominfo,
+                                         libxl_psr_cmt_type type,
+                                         uint32_t nr_sockets)
 {
     char *domain_name;
     uint32_t socketid;
@@ -7822,15 +7823,23 @@ static void psr_cmt_print_domain_cache_occupancy(libxl_dominfo *dominfo,
     free(domain_name);
 
     for (socketid = 0; socketid < nr_sockets; socketid++) {
-        if (!libxl_psr_cmt_get_cache_occupancy(ctx, dominfo->domid, socketid,
-                                               &l3_cache_occupancy))
-            printf("%13u KB", l3_cache_occupancy);
+        switch (type) {
+        case LIBXL_PSR_CMT_TYPE_CACHE_OCCUPANCY:
+            if (!libxl_psr_cmt_get_cache_occupancy(ctx,
+                                                   dominfo->domid,
+                                                   socketid,
+                                                   &l3_cache_occupancy))
+                printf("%13u KB", l3_cache_occupancy);
+            break;
+        default:
+            return;
+        }
     }
 
     printf("\n");
 }
 
-static int psr_cmt_show_cache_occupancy(uint32_t domid)
+static int psr_cmt_show_l3_info(libxl_psr_cmt_type type, uint32_t domid)
 {
     uint32_t i, socketid, nr_sockets, total_rmid;
     uint32_t l3_cache_size;
@@ -7866,19 +7875,22 @@ static int psr_cmt_show_cache_occupancy(uint32_t domid)
         printf("%14s %d", "Socket", socketid);
     printf("\n");
 
-    /* Total L3 cache size */
-    printf("%-46s", "Total L3 Cache Size");
-    for (socketid = 0; socketid < nr_sockets; socketid++) {
-        rc = libxl_psr_cmt_get_l3_cache_size(ctx, socketid, &l3_cache_size);
-        if (rc < 0) {
-            fprintf(stderr,
-                    "Failed to get system l3 cache size for socket:%d\n",
-                    socketid);
-            return -1;
-        }
-        printf("%13u KB", l3_cache_size);
+    if (type == LIBXL_PSR_CMT_TYPE_CACHE_OCCUPANCY) {
+            /* Total L3 cache size */
+            printf("%-46s", "Total L3 Cache Size");
+            for (socketid = 0; socketid < nr_sockets; socketid++) {
+                rc = libxl_psr_cmt_get_l3_cache_size(ctx, socketid,
+                                                     &l3_cache_size);
+                if (rc < 0) {
+                    fprintf(stderr,
+                            "Failed to get system l3 cache size for socket:%d\n",
+                            socketid);
+                    return -1;
+                }
+                printf("%13u KB", l3_cache_size);
+            }
+            printf("\n");
     }
-    printf("\n");
 
     /* Each domain */
     if (domid != INVALID_DOMID) {
@@ -7887,7 +7899,7 @@ static int psr_cmt_show_cache_occupancy(uint32_t domid)
             fprintf(stderr, "Failed to get domain info for %d\n", domid);
             return -1;
         }
-        psr_cmt_print_domain_cache_occupancy(&dominfo, nr_sockets);
+        psr_cmt_print_domain_l3_info(&dominfo, type, nr_sockets);
     }
     else
     {
@@ -7897,7 +7909,7 @@ static int psr_cmt_show_cache_occupancy(uint32_t domid)
             return -1;
         }
         for (i = 0; i < nr_domains; i++)
-            psr_cmt_print_domain_cache_occupancy(list + i, nr_sockets);
+            psr_cmt_print_domain_l3_info(list + i, type, nr_sockets);
         libxl_dominfo_list_free(list, nr_domains);
     }
     return 0;
@@ -7956,7 +7968,7 @@ int main_psr_cmt_show(int argc, char **argv)
 
     switch (type) {
     case LIBXL_PSR_CMT_TYPE_CACHE_OCCUPANCY:
-        ret = psr_cmt_show_cache_occupancy(domid);
+        ret = psr_cmt_show_l3_info(type, domid);
         break;
     default:
         help("psr-cmt-show");
-- 
1.9.1

[PATCH v9 3/3] tools, docs: add total/local memory bandwith monitoring

[Chao Peng]

Add Memory Bandwidth Monitoring(MBM) for VMs. Two types of monitoring
are supported: total and local memory bandwidth monitoring. To use it,
CMT should be enabled in hypervisor.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
Changes in v9:
1. Refactor code in xc_psr_cmt_get_data.
2. Move bandwidth calculation(sleep) from libxl to xl.
3. Broadcast feature with LIBXL_HAVE_PSR_MBM.
4. Check event mask with libxl_psr_cmt_type_supported.
5. Coding style/Document fix.
Changes in v6:
1. Remove DISABLE_IRQ flag as hypervisor disable IRQ for MSR_IA32_TSC
   implicitly.
Changes in v5:
1. Add MBM description in xen command line.
2. Use the tsc from hypervisor directly which is already ns.
3. Call resource_op with DISABLE_IRQ flag.
Changes in v4:
1. Get timestamp from hypervisor and use that for bandwidth calculation.
2. Minor document and coding style fix.
---
 docs/man/xl.pod.1                   | 11 +++++-
 docs/misc/xen-command-line.markdown |  3 ++
 tools/libxc/include/xenctrl.h       |  6 +++-
 tools/libxc/xc_msr_x86.h            |  1 +
 tools/libxc/xc_psr.c                | 68 ++++++++++++++++++++++++++++++-------
 tools/libxl/libxl.h                 | 17 ++++++++++
 tools/libxl/libxl_psr.c             | 44 ++++++++++++++++++++++--
 tools/libxl/libxl_types.idl         |  2 ++
 tools/libxl/xl_cmdimpl.c            | 67 ++++++++++++++++++++++++++++++++++++
 tools/libxl/xl_cmdtable.c           |  4 ++-
 10 files changed, 204 insertions(+), 19 deletions(-)

diff --git a/docs/man/xl.pod.1 b/docs/man/xl.pod.1
index 6b89ba8..cd80ffc 100644
--- a/docs/man/xl.pod.1
+++ b/docs/man/xl.pod.1
@@ -1461,6 +1461,13 @@ is domain level. To monitor a specific domain, just attach the domain id with
 the monitoring service. When the domain doesn't need to be monitored any more,
 detach the domain id from the monitoring service.
 
+Intel Broadwell and later server platforms also offer total/local memory
+bandwidth monitoring. Xen supports per-domain monitoring for these two
+additional monitoring types. Both memory bandwidth monitoring and L3 cache
+occupancy monitoring share the same set of underlying monitoring service. Once
+a domain is attached to the monitoring service, monitoring data can be showed
+for any of these monitoring types.
+
 =over 4
 
 =item B<psr-cmt-attach> [I<domain-id>]
@@ -1475,7 +1482,9 @@ detach: Detach the platform shared resource monitoring service from a domain.
 
 Show monitoring data for a certain domain or all domains. Current supported
 monitor types are:
- - "cache-occupancy": showing the L3 cache occupancy.
+ - "cache-occupancy": showing the L3 cache occupancy(KB).
+ - "total-mem-bandwidth": showing the total memory bandwidth(KB/s).
+ - "local-mem-bandwidth": showing the local memory bandwidth(KB/s).
 
 =back
 
diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index a061aa4..0491dbb 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1097,6 +1097,9 @@ The following resources are available:
   L3 cache occupancy.
   * `cmt` instructs Xen to enable/disable Cache Monitoring Technology.
   * `rmid_max` indicates the max value for rmid.
+* Memory Bandwidth Monitoring (Broadwell and later). Information regarding the
+  total/local memory bandwidth. Follow the same options with Cache Monitoring
+  Technology.
 
 ### reboot
 > `= t[riple] | k[bd] | a[cpi] | p[ci] | n[o] [, [w]arm | [c]old]`
diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index c62f371..8f964ad 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2688,6 +2688,8 @@ int xc_resource_op(xc_interface *xch, uint32_t nr_ops, xc_resource_op_t *ops);
 #if defined(__i386__) || defined(__x86_64__)
 enum xc_psr_cmt_type {
     XC_PSR_CMT_L3_OCCUPANCY,
+    XC_PSR_CMT_TOTAL_MEM_BANDWIDTH,
+    XC_PSR_CMT_LOCAL_MEM_BANDWIDTH,
 };
 typedef enum xc_psr_cmt_type xc_psr_cmt_type;
 int xc_psr_cmt_attach(xc_interface *xch, uint32_t domid);
@@ -2697,10 +2699,12 @@ int xc_psr_cmt_get_domain_rmid(xc_interface *xch, uint32_t domid,
 int xc_psr_cmt_get_total_rmid(xc_interface *xch, uint32_t *total_rmid);
 int xc_psr_cmt_get_l3_upscaling_factor(xc_interface *xch,
                                        uint32_t *upscaling_factor);
+int xc_psr_cmt_get_l3_event_mask(xc_interface *xch, uint32_t *event_mask);
 int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
                                  uint32_t *l3_cache_size);
 int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid, uint32_t cpu,
-                        uint32_t psr_cmt_type, uint64_t *monitor_data);
+                        uint32_t psr_cmt_type, uint64_t *monitor_data,
+                        uint64_t *tsc);
 int xc_psr_cmt_enabled(xc_interface *xch);
 #endif
 
diff --git a/tools/libxc/xc_msr_x86.h b/tools/libxc/xc_msr_x86.h
index 7c3e1a3..7f100e7 100644
--- a/tools/libxc/xc_msr_x86.h
+++ b/tools/libxc/xc_msr_x86.h
@@ -20,6 +20,7 @@
 #ifndef XC_MSR_X86_H
 #define XC_MSR_X86_H
 
+#define MSR_IA32_TSC            0x00000010
 #define MSR_IA32_CMT_EVTSEL     0x00000c8d
 #define MSR_IA32_CMT_CTR        0x00000c8e
 
diff --git a/tools/libxc/xc_psr.c b/tools/libxc/xc_psr.c
index cfae172..5482c8e 100644
--- a/tools/libxc/xc_psr.c
+++ b/tools/libxc/xc_psr.c
@@ -23,6 +23,8 @@
 #define IA32_CMT_CTR_ERROR_MASK         (0x3ull << 62)
 
 #define EVTID_L3_OCCUPANCY             0x1
+#define EVTID_TOTAL_MEM_BANDWIDTH      0x2
+#define EVTID_LOCAL_MEM_BANDWIDTH      0x3
 
 int xc_psr_cmt_attach(xc_interface *xch, uint32_t domid)
 {
@@ -112,6 +114,23 @@ int xc_psr_cmt_get_l3_upscaling_factor(xc_interface *xch,
     return rc;
 }
 
+int xc_psr_cmt_get_l3_event_mask(xc_interface *xch, uint32_t *event_mask)
+{
+    int rc;
+    DECLARE_SYSCTL;
+
+    sysctl.cmd = XEN_SYSCTL_psr_cmt_op;
+    sysctl.u.psr_cmt_op.cmd =
+        XEN_SYSCTL_PSR_CMT_get_l3_event_mask;
+    sysctl.u.psr_cmt_op.flags = 0;
+
+    rc = xc_sysctl(xch, &sysctl);
+    if ( !rc )
+        *event_mask = sysctl.u.psr_cmt_op.u.data;
+
+    return rc;
+}
+
 int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
                                  uint32_t *l3_cache_size)
 {
@@ -139,11 +158,13 @@ int xc_psr_cmt_get_l3_cache_size(xc_interface *xch, uint32_t cpu,
 }
 
 int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid, uint32_t cpu,
-                        xc_psr_cmt_type type, uint64_t *monitor_data)
+                        xc_psr_cmt_type type, uint64_t *monitor_data,
+                        uint64_t *tsc)
 {
     xc_resource_op_t op;
-    xc_resource_entry_t entries[2];
-    uint32_t evtid;
+    xc_resource_entry_t entries[3];
+    xc_resource_entry_t *tsc_entry = NULL;
+    uint32_t evtid, nr = 0;
     int rc;
 
     switch ( type )
@@ -151,33 +172,54 @@ int xc_psr_cmt_get_data(xc_interface *xch, uint32_t rmid, uint32_t cpu,
     case XC_PSR_CMT_L3_OCCUPANCY:
         evtid = EVTID_L3_OCCUPANCY;
         break;
+    case XC_PSR_CMT_TOTAL_MEM_BANDWIDTH:
+        evtid = EVTID_TOTAL_MEM_BANDWIDTH;
+        break;
+    case XC_PSR_CMT_LOCAL_MEM_BANDWIDTH:
+        evtid = EVTID_LOCAL_MEM_BANDWIDTH;
+        break;
     default:
         return -1;
     }
 
-    entries[0].u.cmd = XEN_RESOURCE_OP_MSR_WRITE;
-    entries[0].idx = MSR_IA32_CMT_EVTSEL;
-    entries[0].val = (uint64_t)rmid << 32 | evtid;
-    entries[0].rsvd = 0;
+    entries[nr].u.cmd = XEN_RESOURCE_OP_MSR_WRITE;
+    entries[nr].idx = MSR_IA32_CMT_EVTSEL;
+    entries[nr].val = (uint64_t)rmid << 32 | evtid;
+    entries[nr].rsvd = 0;
+    nr++;
 
-    entries[1].u.cmd = XEN_RESOURCE_OP_MSR_READ;
-    entries[1].idx = MSR_IA32_CMT_CTR;
-    entries[1].val = 0;
-    entries[1].rsvd = 0;
+    entries[nr].u.cmd = XEN_RESOURCE_OP_MSR_READ;
+    entries[nr].idx = MSR_IA32_CMT_CTR;
+    entries[nr].val = 0;
+    entries[nr].rsvd = 0;
+    nr++;
+
+    if ( tsc != NULL )
+    {
+        tsc_entry = &entries[nr];
+        entries[nr].u.cmd = XEN_RESOURCE_OP_MSR_READ;
+        entries[nr].idx = MSR_IA32_TSC;
+        entries[nr].val = 0;
+        entries[nr].rsvd = 0;
+        nr++;
+    }
 
     op.cpu = cpu;
-    op.nr_entries = 2;
+    op.nr_entries = nr;
     op.entries = entries;
 
     rc = xc_resource_op(xch, 1, &op);
     if ( rc < 0 )
         return rc;
 
-    if ( op.result !=2 || entries[1].val & IA32_CMT_CTR_ERROR_MASK )
+    if ( op.result != nr || entries[1].val & IA32_CMT_CTR_ERROR_MASK )
         return -1;
 
     *monitor_data = entries[1].val;
 
+    if ( tsc_entry != NULL )
+        *tsc = tsc_entry->val;
+
     return 0;
 }
 
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 28b6325..9b04927 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -690,6 +690,13 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, libxl_mac *src);
  * If this is defined, the Cache Monitoring Technology feature is supported.
  */
 #define LIBXL_HAVE_PSR_CMT 1
+
+/*
+ * LIBXL_HAVE_PSR_MBM
+ *
+ * If this is defined, the Memory Bandwidth Monitoring feature is supported.
+ */
+#define LIBXL_HAVE_PSR_MBM 1
 #endif
 
 typedef char **libxl_string_list;
@@ -1463,6 +1470,16 @@ int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
                                       uint32_t *l3_cache_occupancy);
 #endif
 
+#ifdef LIBXL_HAVE_PSR_MBM
+int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type);
+int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
+                                           uint32_t domid,
+                                           uint32_t socketid,
+                                           bool     total,
+                                           uint64_t *sample_r,
+                                           uint64_t *tsc_r);
+#endif
+
 /* misc */
 
 /* Each of these sets or clears the flag according to whether the
diff --git a/tools/libxl/libxl_psr.c b/tools/libxl/libxl_psr.c
index 1e1f7ee..ed444e2 100644
--- a/tools/libxl/libxl_psr.c
+++ b/tools/libxl/libxl_psr.c
@@ -161,11 +161,30 @@ out:
     return rc;
 }
 
+int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type)
+{
+    GC_INIT(ctx);
+    uint32_t event_mask;
+    int rc;
+
+    rc = xc_psr_cmt_get_l3_event_mask(ctx->xch, &event_mask);
+    if (rc < 0) {
+        libxl__psr_cmt_log_err_msg(gc, errno);
+        rc = 0;
+    } else {
+        rc = event_mask & (1 << (type - 1));
+    }
+
+    GC_FREE;
+    return rc;
+}
+
 static int libxl__psr_cmt_get_l3_monitoring_data(libxl__gc *gc,
                                                  uint32_t domid,
                                                  xc_psr_cmt_type type,
                                                  uint32_t socketid,
-                                                 uint64_t *data_r)
+                                                 uint64_t *data_r,
+                                                 uint64_t *tsc_r)
 {
     unsigned int rmid;
     uint32_t upscaling_factor;
@@ -187,7 +206,7 @@ static int libxl__psr_cmt_get_l3_monitoring_data(libxl__gc *gc,
         goto out;
     }
 
-    rc = xc_psr_cmt_get_data(CTX->xch, rmid, cpu, type, &monitor_data);
+    rc = xc_psr_cmt_get_data(CTX->xch, rmid, cpu, type, &monitor_data, tsc_r);
     if (rc < 0) {
         LOGE(ERROR, "failed to get monitoring data");
         rc = ERROR_FAIL;
@@ -218,7 +237,7 @@ int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
 
     rc = libxl__psr_cmt_get_l3_monitoring_data(gc, domid,
                                                XC_PSR_CMT_L3_OCCUPANCY,
-                                               socketid, &data);
+                                               socketid, &data, NULL);
     if (rc < 0)
             goto out;
 
@@ -229,6 +248,25 @@ out:
     return rc;
 }
 
+int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
+                                           uint32_t domid,
+                                           uint32_t socketid,
+                                           bool     total,
+                                           uint64_t *sample_r,
+                                           uint64_t *tsc_r)
+{
+    GC_INIT(ctx);
+    int rc;
+    xc_psr_cmt_type type = total ? XC_PSR_CMT_TOTAL_MEM_BANDWIDTH
+                                 : XC_PSR_CMT_LOCAL_MEM_BANDWIDTH;
+
+    rc = libxl__psr_cmt_get_l3_monitoring_data(gc, domid, type, socketid,
+                                               sample_r, tsc_r);
+
+    GC_FREE;
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 1214d2e..46d160e 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -694,4 +694,6 @@ libxl_event = Struct("event",[
 
 libxl_psr_cmt_type = Enumeration("psr_cmt_type", [
     (1, "CACHE_OCCUPANCY"),
+    (2, "TOTAL_MEM_BANDWIDTH"),
+    (3, "LOCAL_MEM_BANDWIDTH"),
     ])
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index a0b50e7..3378e64 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -7807,6 +7807,54 @@ out:
 }
 
 #ifdef LIBXL_HAVE_PSR_CMT
+
+#define MBM_SAMPLE_RETRY_MAX 4
+static int psr_cmt_get_mem_bandwidth(uint32_t domid,
+                                     uint32_t socketid,
+                                     bool     total,
+                                     uint64_t *bandwidth_r)
+{
+    uint64_t sample1, sample2;
+    uint64_t tsc1, tsc2;
+    int retry_attempts = 0;
+    int rc;
+
+    while (1) {
+        rc = libxl_psr_cmt_get_mem_bandwidth_sample(ctx, domid, socketid,
+                                                    total, &sample1, &tsc1);
+        if (rc < 0)
+            return rc;
+
+        usleep(10000);
+
+        rc = libxl_psr_cmt_get_mem_bandwidth_sample(ctx, domid, socketid,
+                                                    total, &sample2, &tsc2);
+        if (rc < 0)
+            return rc;
+
+        if (tsc2 <= tsc1)
+            return -1;
+
+        /*
+         * Hardware guarantees at most 1 overflow can happen if the duration
+         * between two samples is less than 1 second. Note that tsc returned
+         * from hypervisor is already-scaled time(ns).
+         */
+        if (tsc2 - tsc1 < 1000000000 && sample2 >= sample1)
+            break;
+
+        if (retry_attempts < MBM_SAMPLE_RETRY_MAX) {
+            retry_attempts++;
+        } else {
+            fprintf(stderr, "event counter overflowed\n");
+            return -1;
+        }
+    }
+
+    *bandwidth_r = (sample2 - sample1) * 1000000000 / (tsc2 - tsc1) / 1024;
+    return 0;
+}
+
 static void psr_cmt_print_domain_l3_info(libxl_dominfo *dominfo,
                                          libxl_psr_cmt_type type,
                                          uint32_t nr_sockets)
@@ -7814,6 +7862,7 @@ static void psr_cmt_print_domain_l3_info(libxl_dominfo *dominfo,
     char *domain_name;
     uint32_t socketid;
     uint32_t l3_cache_occupancy;
+    uint64_t mem_bandwidth;
 
     if (!libxl_psr_cmt_domain_attached(ctx, dominfo->domid))
         return;
@@ -7831,6 +7880,16 @@ static void psr_cmt_print_domain_l3_info(libxl_dominfo *dominfo,
                                                    &l3_cache_occupancy))
                 printf("%13u KB", l3_cache_occupancy);
             break;
+        case LIBXL_PSR_CMT_TYPE_TOTAL_MEM_BANDWIDTH:
+            if (!psr_cmt_get_mem_bandwidth(dominfo->domid, socketid, true,
+                                           &mem_bandwidth))
+                printf("%11"PRIu64" KB/s", mem_bandwidth);
+            break;
+        case LIBXL_PSR_CMT_TYPE_LOCAL_MEM_BANDWIDTH:
+            if (!psr_cmt_get_mem_bandwidth(dominfo->domid, socketid, false,
+                                           &mem_bandwidth))
+                printf("%11"PRIu64" KB/s", mem_bandwidth);
+            break;
         default:
             return;
         }
@@ -7851,6 +7910,12 @@ static int psr_cmt_show_l3_info(libxl_psr_cmt_type type, uint32_t domid)
         return -1;
     }
 
+    if (!libxl_psr_cmt_type_supported(ctx, type)) {
+        fprintf(stderr, "Monitor type '%s' is not supported in the system\n",
+                libxl_psr_cmt_type_to_string(type));
+        return -1;
+    }
+
     libxl_physinfo_init(&info);
     rc = libxl_get_physinfo(ctx, &info);
     if (rc < 0) {
@@ -7968,6 +8033,8 @@ int main_psr_cmt_show(int argc, char **argv)
 
     switch (type) {
     case LIBXL_PSR_CMT_TYPE_CACHE_OCCUPANCY:
+    case LIBXL_PSR_CMT_TYPE_TOTAL_MEM_BANDWIDTH:
+    case LIBXL_PSR_CMT_TYPE_LOCAL_MEM_BANDWIDTH:
         ret = psr_cmt_show_l3_info(type, domid);
         break;
     default:
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index 4b30d3d..22ab63b 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -538,7 +538,9 @@ struct cmd_spec cmd_table[] = {
       "Show Cache Monitoring Technology information",
       "<PSR-CMT-Type> <Domain>",
       "Available monitor types:\n"
-      "\"cache_occupancy\":         Show L3 cache occupancy\n",
+      "\"cache_occupancy\":         Show L3 cache occupancy(KB)\n"
+      "\"total_mem_bandwidth\":     Show total memory bandwidth(KB/s)\n"
+      "\"local_mem_bandwidth\":     Show local memory bandwidth(KB/s)\n",
     },
 #endif
 };
-- 
1.9.1

Re: [PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[Chao Peng]

On Mon, Feb 02, 2015 at 04:06:06PM +0800, Chao Peng wrote:
> Changes from v8:
> * Merge event mask patch to MBM enabling patch;
> * Address comments from Ian Campbell(Detail in patch itself).

Any comments on this revision?
Thanks,
Chao

Re: [PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[Jan Beulich]

>>> On 04.02.15 at 09:39, <chao.p.peng@linux.intel.com> wrote:
> On Mon, Feb 02, 2015 at 04:06:06PM +0800, Chao Peng wrote:
>> Changes from v8:
>> * Merge event mask patch to MBM enabling patch;
>> * Address comments from Ian Campbell(Detail in patch itself).
> 
> Any comments on this revision?

Please be a little more patient before pinging - you only sent this
2 days ago. Please allow for at least a week.

Jan

Re: [PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[Chao Peng]

On Wed, Feb 04, 2015 at 08:53:28AM +0000, Jan Beulich wrote:
> >>> On 04.02.15 at 09:39, <chao.p.peng@linux.intel.com> wrote:
> > On Mon, Feb 02, 2015 at 04:06:06PM +0800, Chao Peng wrote:
> >> Changes from v8:
> >> * Merge event mask patch to MBM enabling patch;
> >> * Address comments from Ian Campbell(Detail in patch itself).
> > 
> > Any comments on this revision?
> 
> Please be a little more patient before pinging - you only sent this
> 2 days ago. Please allow for at least a week.

Not urgent :) . Please ignore the noise.

Re: [PATCH v9 0/3] enable Memory Bandwidth Monitoring (MBM) for VMs

[Chao Peng]

On Mon, Feb 02, 2015 at 04:06:06PM +0800, Chao Peng wrote:
> Changes from v8:
> * Merge event mask patch to MBM enabling patch;
> * Address comments from Ian Campbell(Detail in patch itself).
> 

I know you guys are still busy but I'd raise it again, to make sure this
revision is not forgotten.

Please still take it easy. Review when you are free is greatly
appreciated.

Thanks,
Chao

Re: [PATCH v9 3/3] tools, docs: add total/local memory bandwith monitoring

[Wei Liu]

On Mon, Feb 02, 2015 at 04:06:09PM +0800, Chao Peng wrote:
> Add Memory Bandwidth Monitoring(MBM) for VMs. Two types of monitoring
> are supported: total and local memory bandwidth monitoring. To use it,
> CMT should be enabled in hypervisor.
> 
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
> Changes in v9:
> 1. Refactor code in xc_psr_cmt_get_data.

Preferably this should be in a separate patch. With the line "No
functional change" in commit message when appropriate.

[...]
>   */
>  #define LIBXL_HAVE_PSR_CMT 1
> +
> +/*
> + * LIBXL_HAVE_PSR_MBM
> + *
> + * If this is defined, the Memory Bandwidth Monitoring feature is supported.
> + */
> +#define LIBXL_HAVE_PSR_MBM 1
>  #endif
>  
>  typedef char **libxl_string_list;
> @@ -1463,6 +1470,16 @@ int libxl_psr_cmt_get_cache_occupancy(libxl_ctx *ctx,
>                                        uint32_t *l3_cache_occupancy);
>  #endif
>  
> +#ifdef LIBXL_HAVE_PSR_MBM
> +int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type);
> +int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
> +                                           uint32_t domid,
> +                                           uint32_t socketid,
> +                                           bool     total,
> +                                           uint64_t *sample_r,
> +                                           uint64_t *tsc_r);

Should the interface be only limited to socket level? Do you (Intel) has
plan to provide bandwidth sampling on finer grain level (say, core
level)?

I also assume that you will never have third type of memory bandwidth?
I.e. do we need to change boolean total to a enum?

Wei.

Re: [PATCH v9 3/3] tools, docs: add total/local memory bandwith monitoring

[Ian Campbell]

On Fri, 2015-02-13 at 13:09 +0000, Wei Liu wrote:
> On Mon, Feb 02, 2015 at 04:06:09PM +0800, Chao Peng wrote: 
> > +#ifdef LIBXL_HAVE_PSR_MBM
> > +int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type);
> > +int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
> > +                                           uint32_t domid,
> > +                                           uint32_t socketid,
> > +                                           bool     total,
> > +                                           uint64_t *sample_r,
> > +                                           uint64_t *tsc_r);
> 
> Should the interface be only limited to socket level? Do you (Intel) has
> plan to provide bandwidth sampling on finer grain level (say, core
> level)?

If we assume not then obviously some h/w designer will implement it ;-)

The existing libxl_psr_cmt_get_l3_cache_size has uint32_t socketid
though, so we may as well do the same here and fixup everything at once
if it ever happens.

> I also assume that you will never have third type of memory bandwidth?
> I.e. do we need to change boolean total to a enum?

There is already an enum, but some of the values it has don't really fit
this interface (the "l3_cache_size" isn't really a stat which needs
sampling), cf my wonder in response to v8 "if wedging all of these
logically unrelated statistics into an umbrella psr interface at the
libxl level makes sense."

Perhaps just call this interface psr_cmt_get_sample, pass it the enum
and always return a tsc? Then other types of stats sampling would fit in
the future, hopefully.

No reason to exclude l3_cache_size from it even if it is a bit pointless
to use this interface for it instead of the dedicated one.

Ian.

Re: [PATCH v9 3/3] tools, docs: add total/local memory bandwith monitoring

[Chao Peng]

On Mon, Feb 23, 2015 at 04:24:32PM +0000, Ian Campbell wrote:
> On Fri, 2015-02-13 at 13:09 +0000, Wei Liu wrote:
> > On Mon, Feb 02, 2015 at 04:06:09PM +0800, Chao Peng wrote: 
> > > +#ifdef LIBXL_HAVE_PSR_MBM
> > > +int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type);
> > > +int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
> > > +                                           uint32_t domid,
> > > +                                           uint32_t socketid,
> > > +                                           bool     total,
> > > +                                           uint64_t *sample_r,
> > > +                                           uint64_t *tsc_r);
> > 
> > Should the interface be only limited to socket level? Do you (Intel) has
> > plan to provide bandwidth sampling on finer grain level (say, core
> > level)?
> 
> If we assume not then obviously some h/w designer will implement it ;-)
> 
> The existing libxl_psr_cmt_get_l3_cache_size has uint32_t socketid
> though, so we may as well do the same here and fixup everything at once
> if it ever happens.

I didn't see any implementation for core-level in the near future from
Intel side but perhaps it's good idea to consider it, at least for long
time. Define the following types achieve this purpose?

libxl_psr_scope_type = Enumeration("psr_scope_type", [
    (1, "SOCKET"),
    ])

libxl_psr_scope = Struct("psr_scope", [
    ("u", KeyedUnion(None, libxl_psr_scope_type, "type",
            ("socket",  integer),
           ])),
], dir=DIR_OUT)

> 
> > I also assume that you will never have third type of memory bandwidth?
> > I.e. do we need to change boolean total to a enum?
> 
> There is already an enum, but some of the values it has don't really fit
> this interface (the "l3_cache_size" isn't really a stat which needs
> sampling), cf my wonder in response to v8 "if wedging all of these
> logically unrelated statistics into an umbrella psr interface at the
> libxl level makes sense."
> 
> Perhaps just call this interface psr_cmt_get_sample, pass it the enum
> and always return a tsc? Then other types of stats sampling would fit in
> the future, hopefully.

For l3_cache_size the tsc will not actually be returned if tsc is NULL.
For the time being, the interface sounds enough for both cache occupancy
and memory bandwidth.

The question is that if I adopt this solution will I remove the original
dedicated l3_cache_size interface? Most concern is api compatibility but
I think it has never been used outside of xl.

Chao
> 
> No reason to exclude l3_cache_size from it even if it is a bit pointless
> to use this interface for it instead of the dedicated one.
> 
> Ian.

Re: [PATCH v9 3/3] tools, docs: add total/local memory bandwith monitoring

[Ian Campbell]

On Wed, 2015-02-25 at 18:21 +0800, Chao Peng wrote:
> On Mon, Feb 23, 2015 at 04:24:32PM +0000, Ian Campbell wrote:
> > On Fri, 2015-02-13 at 13:09 +0000, Wei Liu wrote:
> > > On Mon, Feb 02, 2015 at 04:06:09PM +0800, Chao Peng wrote: 
> > > > +#ifdef LIBXL_HAVE_PSR_MBM
> > > > +int libxl_psr_cmt_type_supported(libxl_ctx *ctx, libxl_psr_cmt_type type);
> > > > +int libxl_psr_cmt_get_mem_bandwidth_sample(libxl_ctx *ctx,
> > > > +                                           uint32_t domid,
> > > > +                                           uint32_t socketid,
> > > > +                                           bool     total,
> > > > +                                           uint64_t *sample_r,
> > > > +                                           uint64_t *tsc_r);
> > > 
> > > Should the interface be only limited to socket level? Do you (Intel) has
> > > plan to provide bandwidth sampling on finer grain level (say, core
> > > level)?
> > 
> > If we assume not then obviously some h/w designer will implement it ;-)
> > 
> > The existing libxl_psr_cmt_get_l3_cache_size has uint32_t socketid
> > though, so we may as well do the same here and fixup everything at once
> > if it ever happens.
> 
> I didn't see any implementation for core-level in the near future from
> Intel side but perhaps it's good idea to consider it, at least for long
> time. Define the following types achieve this purpose?
> 
> libxl_psr_scope_type = Enumeration("psr_scope_type", [
>     (1, "SOCKET"),
>     ])
> 
> libxl_psr_scope = Struct("psr_scope", [
>     ("u", KeyedUnion(None, libxl_psr_scope_type, "type",
>             ("socket",  integer),
>            ])),
> ], dir=DIR_OUT)

That's probably overkill. Simply expanding the socketid parameter to
encode socket/cores (perhaps widening the type) would suffice, wouldn't
it?

All that can wait until there is an actual sub-socket feature to
actually support.
> 
> > 
> > > I also assume that you will never have third type of memory bandwidth?
> > > I.e. do we need to change boolean total to a enum?
> > 
> > There is already an enum, but some of the values it has don't really fit
> > this interface (the "l3_cache_size" isn't really a stat which needs
> > sampling), cf my wonder in response to v8 "if wedging all of these
> > logically unrelated statistics into an umbrella psr interface at the
> > libxl level makes sense."
> > 
> > Perhaps just call this interface psr_cmt_get_sample, pass it the enum
> > and always return a tsc? Then other types of stats sampling would fit in
> > the future, hopefully.
> 
> For l3_cache_size the tsc will not actually be returned if tsc is NULL.

But it will be if tsc != NULL, right?

> For the time being, the interface sounds enough for both cache occupancy
> and memory bandwidth.
> 
> The question is that if I adopt this solution will I remove the original
> dedicated l3_cache_size interface? Most concern is api compatibility but
> I think it has never been used outside of xl.

We can leave the old interface in place (perhaps as a wrapper around the
new one) as a deprecated one for compatibility, that's fine.

If we are really sure it is unused (i.e. libvirt never used it) then we
could consider removing it, there's an extent to which ABI compatibility
is a bit like a tree falling in the woods...

Ian.