1LIBPFM(3)                  Linux Programmer's Manual                 LIBPFM(3)
2
3
4

NAME

6       libpfm_intel_snb - support for Intel Sandy Bridge core PMU
7

SYNOPSIS

9       #include <perfmon/pfmlib.h>
10
11       PMU name: snb
12       PMU desc: Intel Sandy Bridge
13       PMU name: snb_ep
14       PMU desc: Intel Sandy Bridge EP
15
16

DESCRIPTION

18       The  library  supports  the  Intel  Sandy Bridge core PMU. It should be
19       noted that this PMU model only covers  each  core's  PMU  and  not  the
20       socket  level  PMU.  For that refer to the Sandy Bridge uncore PMU sup‐
21       port.
22
23       On Sandy Bridge, the number of generic counters depends on  the  Hyper‐
24       threading  (HT)  mode.  When HT is on, then only 4 generic counters are
25       available. When HT is off, then 8 generic counters are  available.  The
26       pfm_get_pmu_info() function returns the maximum number of generic coun‐
27       ters in num_cntrs.
28
29

MODIFIERS

31       The following modifiers are supported on Intel Sandy Bridge processors:
32
33       u      Measure at user level which includes privilege levels 1,  2,  3.
34              This corresponds to PFM_PLM3.  This is a boolean modifier.
35
36       k      Measure  at  kernel level which includes privilege level 0. This
37              corresponds to PFM_PLM0.  This is a boolean modifier.
38
39       i      Invert the meaning of the event.  The  counter  will  now  count
40              cycles  in  which  the event is not occurring. This is a boolean
41              modifier
42
43       e      Enable edge detection, i.e., count only when there  is  a  state
44              transition  from  no  occurrence  of  the  event to at least one
45              occurrence. This modifier must be combined with a  counter  mask
46              modifier  (m)  with  a value greater or equal to one.  This is a
47              boolean modifier.
48
49       c      Set the counter mask value. The mask acts as  a  threshold.  The
50              counter  will  count the number of cycles in which the number of
51              occurrences of the event is greater or equal to  the  threshold.
52              This is an integer modifier with values in the range [0:255].
53
54       t      Measure  on both threads at the same time assuming hyper-thread‐
55              ing is enabled. This is a boolean modifier.
56
57       ldlat  Pass       a       latency        threshold        to        the
58              MEM_TRANS_RETIRED:LATENCY_ABOVE_THRESHOLD  event.   This  is  an
59              integer attribute that must be in the  range  [3:65535].  It  is
60              required  for this event.  Note that the event must be used with
61              precise sampling (PEBS).
62
63

OFFCORE_RESPONSE events

65       Intel Sandy Bridge provides two  offcore_response  events,  like  Intel
66       Westmere.  They are called OFFCORE_RESPONSE_0 and OFFCORE_RESPONSE_1.
67
68       Those  events  need special treatment in the performance monitoring in‐
69       frastructure because each event uses an extra register  to  store  some
70       settings.  Thus, in case multiple offcore_response events are monitored
71       simultaneously, the kernel needs to manage the sharing  of  that  extra
72       register.
73
74       The  offcore_response  events  are  exposed  as  a normal events by the
75       library. The extra settings are exposed as regular umasks. The  library
76       takes  care  of  encoding the events according to the underlying kernel
77       interface.
78
79       On Intel Sandy Bridge, the umasks are divided  into  three  categories:
80       request,  supplier  and snoop. The user must provide at least one umask
81       for each category. The categories are shown in the umask descriptions.
82
83       There is also the special response umask called ANY_RESPONSE. When this
84       umask is used then it overrides any supplier and snoop umasks. In other
85       words, users can specify either ANY_RESPONSE  OR  any  combinations  of
86       supplier + snoops.
87
88       In  case  no  supplier  or  snoop is specified, the library defaults to
89       using ANY_RESPONSE.
90
91       For instance, the following are valid event selections:
92
93       OFFCORE_RESPONSE_0:DMND_DATA_RD:ANY_RESPONSE
94
95       OFFCORE_RESPONSE_0:ANY_REQUEST
96
97       OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY
98
99
100       But the following are illegal:
101
102
103       OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:ANY_RESPONSE
104
105       OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY:ANY_RESPONSE
106
107

SEE ALSO

109       libpfm_snb_unc(3)
110
111

AUTHORS

113       Stephane Eranian <eranian@gmail.com>
114
115
116
117                                 January, 2011                       LIBPFM(3)