LIBPFM(3) Linux Programmer's Manual LIBPFM(3)NAMElibpfm_intel_nhm - support for Intel Nehalem core PMU
SYNOPSIS
#include <perfmon/pfmlib.h>
PMU name: nhm
PMU desc: Intel Nehalem
PMU name: nhm_ex
PMU desc: Intel Nehalem EX
DESCRIPTION
The library supports the Intel Nehalem core PMU. It should be noted
that this PMU model only covers the each core's PMU and not the socket
level PMU. It is provided separately. Support is provided for the Intel
Core i7 and Core i5 processors.
MODIFIERS
The following modifiers are supported on Intel Nehalem processors:
u Measure at user level which includes privilege levels 1, 2, 3.
This corresponds to PFM_PLM3. This is a boolean modifier.
k Measure at kernel level which includes privilege level 0. This
corresponds to PFM_PLM0. This is a boolean modifier.
i Invert the meaning of the event. The counter will now count
cycles in which the event is not occurring. This is a boolean
modifier
e Enable edge detection, i.e., count only when there is a state
transition from no occurrence of the event to at least one
occurrence. This modifier must be combined with a counter mask
modifier (m) with a value greater or equal to one. This is a
boolean modifier.
c Set the counter mask value. The mask acts as a threshold. The
counter will count the number of cycles in which the number of
occurrences of the event is greater or equal to the threshold.
This is an integer modifier with values in the range [0:255].
t Measure on both threads at the same time assuming hyper-thread‐
ing is enabled. This is a boolean modifier.
ldlat Pass a latency threshold to the
MEM_INST_RETIRED:LATENCY_ABOVE_THRESHOLD event. This is an
integer attribute that must be in the range [3:65535]. It is
required for this event. Note that the event must be used with
precise sampling (PEBS).
OFFCORE_RESPONSE event
The library is able to encode the OFFCORE_RESPONSE_0 event. This is a
special event because it needs a second MSR (0x1a6) to be programmed
for the event to count properly. Thus two values are necessary. The
first value can be programmed on any of the generic counters. The sec‐
ond value goes into the dedicated MSR (0x1a6).
The OFFCORE_RESPONSE event is exposed as a normal event with several
umasks which are divided in two groups: request and response. The user
must provide at least one umask from each group. For instance, OFF‐
CORE_RESPONSE_0:ANY_DATA:LOCAL_DRAM.
When using pfm_get_event_encoding(), two 64-bit values are returned.
The first value corresponds to what needs to be programmed into any of
the generic counters. The second value must be programmed into the ded‐
icated MSR (0x1a6).
When using an OS-specific encoding routine, the way the event is
encoded is OS specific. Refer to the corresponding man page for more
information.
AUTHORS
Stephane Eranian <eranian@gmail.com>
September, 2009 LIBPFM(3)
