libpfm_intel_skl - support for Intel SkyLake core PMU
#include <perfmon/pfmlib.h>
PMU name: skl
PMU desc: Intel SkyLake
The library supports the Intel SkyLake core PMU. It should be
noted that this PMU model only covers each core's PMU and not the socket
level PMU.
On SkyLake, the number of generic counters depends on the
Hyperthreading (HT) mode.
counters are available. The pfm_get_pmu_info() function
returns the maximum number of generic counters in num_cntrs.
The following modifiers are supported on Intel SkyLake
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-threading is
enabled. This is a boolean modifier.
- ldlat
- Pass a latency threshold to the MEM_TRANS_RETIRED:LOAD_LATENCY event. This
is an integer attribute that must be in the range [1:65535]. It is
required for this event. Note that the event must be used with precise
sampling (PEBS).
- intx
- Monitor the event only when executing inside a transactional memory region
(in tx). Event does not count otherwise. This is a boolean modifiers.
Default value is 0.
- intxcp
- Do not count occurrences of the event when they are inside an aborted
transactional memory region. This is a boolean modifier. Default value is
0.
- fe_thres
- This modifier is for the FRONTEND_RETIRED event only. It defines the
period in core cycles after which the IDQ_*_BUBBLES umask counts. It acts
as a threshold, i.e., at least a period of N core cycles where the
frontend did not deliver X uops. It can only be used with the
IDQ_*_BUBBLES umasks. If not specified, the default threshold value is 1
cycle. the valid values are in [1-4095].
Intel SkyLake provides two offcore_response events. They are
called OFFCORE_RESPONSE_0 and OFFCORE_RESPONSE_1.
Those events need special treatment in the performance monitoring
infrastructure because each event uses an extra register to store some
settings. Thus, in case multiple offcore_response events are monitored
simultaneously, the kernel needs to manage the sharing of that extra
register.
The offcore_response events are exposed as a normal events by the
library. The extra settings are exposed as regular umasks. The library takes
care of encoding the events according to the underlying kernel
interface.
On Intel SkyLake, the umasks are divided into three categories:
request, supplier and snoop. The user must provide at least one umask for
each category. The categories are shown in the umask descriptions.
There is also the special response umask called
ANY_RESPONSE. When this umask is used then it overrides any supplier
and snoop umasks. In other words, users can specify either
ANY_RESPONSE OR any combinations of supplier + snoops.
In case no supplier or snoop is specified, the library defaults to
using ANY_RESPONSE.
For instance, the following are valid event selections:
- OFFCORE_RESPONSE_0:DMND_DATA_RD:ANY_RESPONSE
- OFFCORE_RESPONSE_0:ANY_REQUEST
- OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY
-
But the following are illegal:
- OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:ANY_RESPONSE
- OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY:ANY_RESPONSE
-
Stephane Eranian <eranian@gmail.com>