This patch enables statistics from the Arm PMUv3 through the perfmon
plugin.
In comparison to using the Linux "perf" tool, it allows obtaining
direct, per node level statistics (rather than per thread). By accessing
the PMU counter registers directly from userspace, we can avoid the
overhead of using a read() system call and get more accurate and fine
grained statistics about the running of individual nodes.
A demo of perfmon on Arm can be found at:
https://asciinema.org/a/egVNN1OF7JEKHYmfl5bpDYxfF
*Important Note*
Perfmon on Arm is dependent on and works only on Linux kernel versions
of v5.17+ as this is when userspace access to Arm perf counters was
included.
On most Arm systems, a maximum of 7 PMU events can be configured at once
- (6x PMU events + 1x CPU_CYCLE counter). If some perf counters are in
use elsewhere by other applications, and there are insufficient counters
remaining to open the bundle, the perf_event_open call will fail
(provided the events are grouped with the group_fd param, which perfmon
currently utilises).
See arm/events.h for a list of PMUv3 events available, although it is
implementation defined whether most events are implemented or not. Only
a small set of 7 events is required to be implemented in Armv8.0, with
some additional events required in later versions. As such, depending on
the implementation, some statistics may not be available. See Arm
Architecture Reference Manual for Armv8-A, D7.10.2 "The PMU event number
space and common events" for more information.
arm/events.c:arm_init() gets information from the sysfs about what
events are implemented on a particular CPU at runtime. Arm's
implementation of the perfmon source callback .bundle_support uses this
information to disable unsupported events in a bundle, or in the case
no events are supported, disable the entire bundle.
Where a particular event in a bundle is not implemented, the statistic
for that event is shown as '-' in the 'show perfmon statistics' cli
output, by disabling the column.
There is additional code in perfmon.c to only open events which are
marked as implemented. Since we're only opening and reading events that
are implemented, some extra logic is required in cli.c to re-align
either perfmon_node_stats_t or perfmon_reading_t with the column
headings configured in each bundle, taking into account disabled
columns.
Userspace access to perf counters is disabled by default, and needs to
be enabled with 'sudo sysctl kernel/perf_user_access=1'.
There is a check built into the Arm event source init function
(arm/events.c:arm_init) to check that userspace reading of perf counters
is enabled in the /proc/sys/kernel/perf_user_access file.
If the above file does not exist, it means the kernel version is
unsupported. Users without a supported kernel will see a warning
message, and no Arm bundles will be registered to use in perfmon.
Enabling/using plugin:
- include the following in startup.conf:
- plugins { plugin perfmon_plugin.so { enable }
- 'show perfmon bundle [verbose]' - show available statistics bundles
- 'perfmon start bundle <bundle-name>' - enable and start logging
- 'perfmon stop' - stop logging
- 'show perfmon statistics' - show output
For a general guide on using and understanding Arm PMUv3 events, see
https://community.arm.com/arm-community-blogs/b/tools-software-ides-blog/posts/arm-neoverse-n1-performance-analysis-methodology
Type: feature
Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
Tested-by: Jieqiang Wang <jieqiang.wang@arm.com>
Change-Id: I0620fe5b1bbe78842dfb1d0b6a060bb99e777651
In preparation for enabling perfmon on Arm platforms, move some Intel
/arch specific logic into the /intel directory and update the CMake to
split the common code from arch specific files.
Since the dispatch_wrapper code is very different on Arm/Intel,
each arch can provide their own implementation + conduct any additional
arch specific config e.g. on Intel, all indexes from the mmap pages are
cached. The new method intel_config_dispatch_wrapper conducts this
config and returns a pointer to the dispatch wrapper to use.
Similarly, is_bundle_supported() looks very different on Arm/Intel, so
each implementation is to provide their own arch specific checks.
Two new callbacks/function ptrs are added in PERFMON_REGISTER_SOURCE to
support this - .bundle_support and .config_dispatch_wrapper.
Type: refactor
Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
Change-Id: Idd121ddcfd1cc80a57c949cecd64eb2db0ac8be3
Breakdown the distribution of uops delivered to the frontend.
Collerates directly with the source of the uops.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I93a57dbe56dfa0f378527844aa4e63f45a548e55
Topdown level 1 and 2 for Intel Ice Lake (ICX). Limiting topdown support
to THREAD for the moment on Ice Lake, as NODE support is still
unreliable. Also removing Topdown Level 1 from Sapphire Rapids onwards,
as Topdown LeveL 2 also shows Level 1 on Sapphire, and it reduces the
overall number of bundles.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: Iaa68b711dc8b6fb1090880b411debadb3c37f8bc
Add a bundle to measure topdown backend bound core cycles, will indicate if any
given execution port has contention.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I37d1b38c101ac42d51c10fa4452b822d34b729c9
Rename the memory bandwidth bundle to memory stalls, to differentiate it
from the bundle that measures memory controller bandwidth boundedness.
Type: refactor
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I828c73b6f769046e1ab592712bdf81ceefcd7911
Added an Intel Ice Lake specific bundles to measure pci bandwidth through the
Intel IO PMU. The "PCI" bundle measures read/writes from pci devices. The "CPU"
bundle measure read/writes from cpus to pci devices.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: Id48cef5988113e8dc4690b97d22243311bfa7961
Enable Topdown Level 1 support on Snowridge,
enabled with standard CPU events on small core.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I58ad09383de7464265ac1b69e683f253591e3b5e
This code seems really usefull for reuse in
other plugins, for pretty table formatting
Type: feature
Change-Id: Ib5784a0dfc81b7d5a5d1f5ccdd02072e460a50fb
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>
Added memory bandwidth boundedness bundle, closely related to cache-hierarchy.
This bundle works on ICX only, due to an ICX specific counter.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: Id385bd5f4e645ac020774e311c623afb64b79b1e
Adding perfmon node TMAM support on ICX.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I48a9a9ff6a72efc28eaf0cb11ef39fb62cebb126
Show % time spent per graph node in power level 0, 1 and 2.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: I678ee812fa993af39568e9f9dfbf2396fc13ad42
Add branches, branches taken (a meteric for branchy code), and branch
misses.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: If92d4aaf9d0a6e3b99b8c19e6311cc08ca470590
Added basic support for counting cache hits and misses per node.
Type: improvement
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
Change-Id: Ic566611fd3d4246ccaa2117d8f74a569a6862e80
Callbacks for monitoring and performance measurement:
- Add new callback list type, with context
- Add callbacks for API, CLI, and barrier sync
- Modify node dispatch callback to pass plugin-specific context
- Modify perfmon plugin to keep PMC samples local to the plugin
- Include process nodes in dispatch callback
- Pass dispatch function return value to callback
Type: refactor
Signed-off-by: Tom Seidenberg <tseidenb@cisco.com>
Change-Id: I28b06c58490611e08d76ff5b01b2347ba2109b22
The license issue is resolved, so we can package the .json
files. Added to the vpp-dev package in .tar.xz form, which saves a lot
of space.
Updated the perfmon error log entry: tell folks where to find the
compressed tarball, and how to extract it.
Change-Id: I3ed351fbf154cc3ba22d5f9c666acff77a2a14cf
Signed-off-by: Dave Barach <dave@barachs.net>
