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This test case fails on s390 virtual machine z/VM which has no PMU support
when the perf tool is built with LIBPFM4=1.
Using make LIBPFM4=1 builds the perf tool with support for libpfm
event notation. The command line flag --pfm-events is valid:
# ./perf record --pfm-events cycles -- true
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.001 MB perf.data (2 samples) ]
#
However the command 'perf test -Fv 17' fails on s390 z/VM virtual machine
with LIBPFM4=1:
# perf test -Fv 17
17: Setup struct perf_event_attr :
--- start ---
.....
running './tests/attr/test-record-group2'
unsupp './tests/attr/test-record-group2'
running './tests/attr/test-record-pfm-period'
expected exclude_hv=0, got 1
FAILED './tests/attr/test-record-pfm-period' - match failure
---- end ----
Setup struct perf_event_attr: FAILED!
When --pfm-event system is not supported, the test returns unsupported
and continues. Here is an example using a virtual machine on x86 and
Fedora 34:
[root@f33 perf]# perf test -Fv 17
17: Setup struct perf_event_attr :
--- start ---
.....
running './tests/attr/test-record-group2'
unsupp './tests/attr/test-record-group2'
running './tests/attr/test-record-pfm-period'
unsupp './tests/attr/test-record-pfm-period'
....
The issue is file ./tests/attr/test-record-pfm-period
which requires perf event attribute member exclude_hv to be zero.
This is not the case on s390 where the value of exclude_hv is one when
executing on a z/VM virtual machine without PMU hardware support.
Fix this by allowing value exlucde_hv to be zero or one.
Output before:
# /usr/bin/python ./tests/attr.py -d ./tests/attr/ -t \
test-record-pfm-period -p ./perf -vvv 2>&1| fgrep match
matching [event:base-record]
match: [event:base-record] matches []
FAILED './tests/attr//test-record-pfm-period' - match failure
#
Output after:
# /usr/bin/python ./tests/attr.py -d ./tests/attr/ -t \
test-record-pfm-period -p ./perf -vvv 2>&1| fgrep match
matching [event:base-record]
match: [event:base-record] matches ['event-1-0-6', 'event-1-0-5']
matched
Background:
Using libpfm library ends up in this function call sequence
pfm_get_perf_event_encoding()
+-- pfm_get_os_event_encoding()
+-- pfmlib_perf_event_encode()
is called when no hardware specific PMU unit can be detected
as in the s390 z/VM virtual machine case. This uses the
"perf_events generic PMU" data structure which sets exclude_hv
to 1 per default. Using this PMU that test case always fails.
That is the reason why exclude_hv attribute setting varies.
Version 2:
As suggested by Ian Rogers make perf_event_attribute member
exclude_hv more robust and accept value 0 or 1 to handle more
test cases which might fail on s390 virtual machine z/VM.
Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20210528091050.245838-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.