mirror of
https://github.com/torvalds/linux.git
synced 2024-12-04 18:13:04 +00:00
751d5b2741
Fix thirty five typos in dm-integrity.rst, dm-raid.rst, dm-zoned.rst, verity.rst, writecache.rst, tsx_async_abort.rst, md.rst, bttv.rst, dvb_references.rst, frontend-cardlist.rst, gspca-cardlist.rst, ipu3.rst, remote-controller.rst, mm/index.rst, numaperf.rst, userfaultfd.rst, module-signing.rst, imx-ddr.rst, intel-speed-select.rst, intel_pstate.rst, ramoops.rst, abi.rst, kernel.rst, vm.rst Signed-off-by: Andrew Klychkov <andrew.a.klychkov@gmail.com> Link: https://lore.kernel.org/r/20201204072848.GA49895@spblnx124.lan Signed-off-by: Jonathan Corbet <corbet@lwn.net>
72 lines
3.5 KiB
ReStructuredText
72 lines
3.5 KiB
ReStructuredText
=====================================================
|
|
Freescale i.MX8 DDR Performance Monitoring Unit (PMU)
|
|
=====================================================
|
|
|
|
There are no performance counters inside the DRAM controller, so performance
|
|
signals are brought out to the edge of the controller where a set of 4 x 32 bit
|
|
counters is implemented. This is controlled by the CSV modes programmed in counter
|
|
control register which causes a large number of PERF signals to be generated.
|
|
|
|
Selection of the value for each counter is done via the config registers. There
|
|
is one register for each counter. Counter 0 is special in that it always counts
|
|
“time” and when expired causes a lock on itself and the other counters and an
|
|
interrupt is raised. If any other counter overflows, it continues counting, and
|
|
no interrupt is raised.
|
|
|
|
The "format" directory describes format of the config (event ID) and config1
|
|
(AXI filtering) fields of the perf_event_attr structure, see /sys/bus/event_source/
|
|
devices/imx8_ddr0/format/. The "events" directory describes the events types
|
|
hardware supported that can be used with perf tool, see /sys/bus/event_source/
|
|
devices/imx8_ddr0/events/. The "caps" directory describes filter features implemented
|
|
in DDR PMU, see /sys/bus/events_source/devices/imx8_ddr0/caps/.
|
|
|
|
.. code-block:: bash
|
|
|
|
perf stat -a -e imx8_ddr0/cycles/ cmd
|
|
perf stat -a -e imx8_ddr0/read/,imx8_ddr0/write/ cmd
|
|
|
|
AXI filtering is only used by CSV modes 0x41 (axid-read) and 0x42 (axid-write)
|
|
to count reading or writing matches filter setting. Filter setting is various
|
|
from different DRAM controller implementations, which is distinguished by quirks
|
|
in the driver. You also can dump info from userspace, filter in "caps" directory
|
|
indicates whether PMU supports AXI ID filter or not; enhanced_filter indicates
|
|
whether PMU supports enhanced AXI ID filter or not. Value 0 for un-supported, and
|
|
value 1 for supported.
|
|
|
|
* With DDR_CAP_AXI_ID_FILTER quirk(filter: 1, enhanced_filter: 0).
|
|
Filter is defined with two configuration parts:
|
|
--AXI_ID defines AxID matching value.
|
|
--AXI_MASKING defines which bits of AxID are meaningful for the matching.
|
|
|
|
- 0: corresponding bit is masked.
|
|
- 1: corresponding bit is not masked, i.e. used to do the matching.
|
|
|
|
AXI_ID and AXI_MASKING are mapped on DPCR1 register in performance counter.
|
|
When non-masked bits are matching corresponding AXI_ID bits then counter is
|
|
incremented. Perf counter is incremented if::
|
|
|
|
AxID && AXI_MASKING == AXI_ID && AXI_MASKING
|
|
|
|
This filter doesn't support filter different AXI ID for axid-read and axid-write
|
|
event at the same time as this filter is shared between counters.
|
|
|
|
.. code-block:: bash
|
|
|
|
perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
|
|
perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
|
|
|
|
.. note::
|
|
|
|
axi_mask is inverted in userspace(i.e. set bits are bits to mask), and
|
|
it will be reverted in driver automatically. so that the user can just specify
|
|
axi_id to monitor a specific id, rather than having to specify axi_mask.
|
|
|
|
.. code-block:: bash
|
|
|
|
perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12
|
|
|
|
* With DDR_CAP_AXI_ID_FILTER_ENHANCED quirk(filter: 1, enhanced_filter: 1).
|
|
This is an extension to the DDR_CAP_AXI_ID_FILTER quirk which permits
|
|
counting the number of bytes (as opposed to the number of bursts) from DDR
|
|
read and write transactions concurrently with another set of data counters.
|