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authorXu Yilun <yilun.xu@intel.com>2020-04-27 04:06:22 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-28 16:49:28 +0300
commit1f03ac9460cf0c4886fc8a72fb3d0cd479b59bca (patch)
treeb59e493f1781deefe77f02858412ad8e1c14a4d1 /Documentation/fpga/dfl.rst
parenta2cc220a9a9227b2c5c9b39f57340bce64f040fd (diff)
downloadlinux-1f03ac9460cf0c4886fc8a72fb3d0cd479b59bca.tar.xz
Documentation: fpga: dfl: add description for performance reporting support
This patch adds description for performance reporting support for Device Feature List (DFL) based FPGA. Signed-off-by: Xu Yilun <yilun.xu@intel.com> Signed-off-by: Wu Hao <hao.wu@intel.com> Link: https://lore.kernel.org/r/1587949583-12058-2-git-send-email-hao.wu@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/fpga/dfl.rst')
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diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
index 094fc8aacd8e..978c4af416a4 100644
--- a/Documentation/fpga/dfl.rst
+++ b/Documentation/fpga/dfl.rst
@@ -118,6 +118,11 @@ More functions are exposed through sysfs
management information (current temperature, thresholds, threshold status,
etc.).
+ Performance reporting
+ performance counters are exposed through perf PMU APIs. Standard perf tool
+ can be used to monitor all available perf events. Please see performance
+ counter section below for more detailed information.
+
FIU - PORT
==========
@@ -378,6 +383,85 @@ The device nodes used for ioctl() or mmap() can be referenced through::
/sys/class/fpga_region/<regionX>/<dfl-port.n>/dev
+Performance Counters
+====================
+Performance reporting is one private feature implemented in FME. It could
+supports several independent, system-wide, device counter sets in hardware to
+monitor and count for performance events, including "basic", "cache", "fabric",
+"vtd" and "vtd_sip" counters. Users could use standard perf tool to monitor
+FPGA cache hit/miss rate, transaction number, interface clock counter of AFU
+and other FPGA performance events.
+
+Different FPGA devices may have different counter sets, depending on hardware
+implementation. E.g., some discrete FPGA cards don't have any cache. User could
+use "perf list" to check which perf events are supported by target hardware.
+
+In order to allow user to use standard perf API to access these performance
+counters, driver creates a perf PMU, and related sysfs interfaces in
+/sys/bus/event_source/devices/dfl_fme* to describe available perf events and
+configuration options.
+
+The "format" directory describes the format of the config field of struct
+perf_event_attr. There are 3 bitfields for config: "evtype" defines which type
+the perf event belongs to; "event" is the identity of the event within its
+category; "portid" is introduced to decide counters set to monitor on FPGA
+overall data or a specific port.
+
+The "events" directory describes the configuration templates for all available
+events which can be used with perf tool directly. For example, fab_mmio_read
+has the configuration "event=0x06,evtype=0x02,portid=0xff", which shows this
+event belongs to fabric type (0x02), the local event id is 0x06 and it is for
+overall monitoring (portid=0xff).
+
+Example usage of perf::
+
+ $# perf list |grep dfl_fme
+
+ dfl_fme0/fab_mmio_read/ [Kernel PMU event]
+ <...>
+ dfl_fme0/fab_port_mmio_read,portid=?/ [Kernel PMU event]
+ <...>
+
+ $# perf stat -a -e dfl_fme0/fab_mmio_read/ <command>
+ or
+ $# perf stat -a -e dfl_fme0/event=0x06,evtype=0x02,portid=0xff/ <command>
+ or
+ $# perf stat -a -e dfl_fme0/config=0xff2006/ <command>
+
+Another example, fab_port_mmio_read monitors mmio read of a specific port. So
+its configuration template is "event=0x06,evtype=0x01,portid=?". The portid
+should be explicitly set.
+
+Its usage of perf::
+
+ $# perf stat -a -e dfl_fme0/fab_port_mmio_read,portid=0x0/ <command>
+ or
+ $# perf stat -a -e dfl_fme0/event=0x06,evtype=0x02,portid=0x0/ <command>
+ or
+ $# perf stat -a -e dfl_fme0/config=0x2006/ <command>
+
+Please note for fabric counters, overall perf events (fab_*) and port perf
+events (fab_port_*) actually share one set of counters in hardware, so it can't
+monitor both at the same time. If this set of counters is configured to monitor
+overall data, then per port perf data is not supported. See below example::
+
+ $# perf stat -e dfl_fme0/fab_mmio_read/,dfl_fme0/fab_port_mmio_write,\
+ portid=0/ sleep 1
+
+ Performance counter stats for 'system wide':
+
+ 3 dfl_fme0/fab_mmio_read/
+ <not supported> dfl_fme0/fab_port_mmio_write,portid=0x0/
+
+ 1.001750904 seconds time elapsed
+
+The driver also provides a "cpumask" sysfs attribute, which contains only one
+CPU id used to access these perf events. Counting on multiple CPU is not allowed
+since they are system-wide counters on FPGA device.
+
+The current driver does not support sampling. So "perf record" is unsupported.
+
+
Add new FIUs support
====================
It's possible that developers made some new function blocks (FIUs) under this