selftests/resctrl: Discover SNC kernel support and adjust messages

Resctrl selftest prints a message on test failure that Sub-Numa
Clustering (SNC) could be enabled and points the user to check thei

selftests/resctrl: Discover SNC kernel support and adjust messages

Resctrl selftest prints a message on test failure that Sub-Numa
Clustering (SNC) could be enabled and points the user to check their BIOS
settings. No actual check is performed before printing that message so
it is not very accurate in pinpointing a problem.

When there is SNC support for kernel's resctrl subsystem and SNC is
enabled then sub node files are created for each node in the resctrlfs.
The sub node files exist in each regular node's L3 monitoring directory.
The reliable path to check for existence of sub node files is
/sys/fs/resctrl/mon_data/mon_L3_00/mon_sub_L3_00.

Add helper that checks for mon_sub_L3_00 existence.

Correct old messages to account for kernel support of SNC in
resctrl.

Signed-off-by: Maciej Wieczor-Retman <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Adjust effective L3 cache size with SNC enabled

Sub-NUMA Cluster divides CPUs sharing an L3 cache into separate NUMA
nodes. Systems may support splitting into either two, three, f

selftests/resctrl: Adjust effective L3 cache size with SNC enabled

Sub-NUMA Cluster divides CPUs sharing an L3 cache into separate NUMA
nodes. Systems may support splitting into either two, three, four or six
nodes. When SNC mode is enabled the effective amount of L3 cache
available for allocation is divided by the number of nodes per L3.

It's possible to detect which SNC mode is active by comparing the number
of CPUs that share a cache with CPU0, with the number of CPUs on node0.

Detect SNC mode once and let other tests inherit that information.

Update CFLAGS after including lib.mk in the Makefile so that fallthrough
macro can be used.

To check if SNC detection is reliable one can check the
/sys/devices/system/cpu/offline file. If it's empty, it means all cores
are operational and the ratio should be calculated correctly. If it has
any contents, it means the detected SNC mode can't be trusted and should
be disabled.

Check if detection was not reliable due to offline cpus. If it was skip
running tests since the results couldn't be trusted.

Co-developed-by: Tony Luck <[email protected]>
Signed-off-by: Tony Luck <[email protected]>
Signed-off-by: Maciej Wieczor-Retman <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Remove unused measurement code

The MBM and MBA resctrl selftests run a benchmark during which
it takes measurements of read memory bandwidth via perf.
Code exists to support measu

selftests/resctrl: Remove unused measurement code

The MBM and MBA resctrl selftests run a benchmark during which
it takes measurements of read memory bandwidth via perf.
Code exists to support measurements of write memory bandwidth
but there exists no path with which this code can execute.

While code exists for write memory bandwidth measurement
there has not yet been a use case for it. Remove this unused code.
Rename relevant functions to include "read" so that it is clear
that it relates only to memory bandwidth reads, while renaming
the functions also add consistency by changing the "membw"
instances to more prevalent "mem_bw".

Signed-off-by: Reinette Chatre <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Protect against array overflow when reading strings

resctrl selftests discover system properties via a variety of sysfs files.
The MBM and MBA tests need to discover the event and

selftests/resctrl: Protect against array overflow when reading strings

resctrl selftests discover system properties via a variety of sysfs files.
The MBM and MBA tests need to discover the event and umask with which to
configure the performance event used to measure read memory bandwidth.
This is done by parsing the contents of
/sys/bus/event_source/devices/uncore_imc_<imc instance>/events/cas_count_read
Similarly, the resctrl selftests discover the cache size via
/sys/bus/cpu/devices/cpu<id>/cache/index<index>/size.

Take care to do bounds checking when using fscanf() to read the
contents of files into a string buffer because by default fscanf() assumes
arbitrarily long strings. If the file contains more bytes than the array
can accommodate then an overflow will occur.

Provide a maximum field width to the conversion specifier to protect
against array overflow. The maximum is one less than the array size because
string input stores a terminating null byte that is not covered by the
maximum field width.

Signed-off-by: Reinette Chatre <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Remove test name comparing from write_bm_pid_to_resctrl()

write_bm_pid_to_resctrl() uses resctrl_val to check test name which is
not a good interface generic resctrl FS functions

selftests/resctrl: Remove test name comparing from write_bm_pid_to_resctrl()

write_bm_pid_to_resctrl() uses resctrl_val to check test name which is
not a good interface generic resctrl FS functions should provide.

Tests define mongrp when needed. Remove the test name check in
write_bm_pid_to_resctrl() to only rely on the mongrp parameter being
non-NULL.

Remove write_bm_pid_to_resctrl() resctrl_val parameter and resctrl_val
member from the struct resctrl_val_param that are not used anymore.
Similarly, remove the test name constants that are no longer used.

Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Convert ctrlgrp & mongrp to pointers

The struct resctrl_val_param has control and monitor groups as char
arrays but they are not supposed to be mutated within resctrl_val().

Conv

selftests/resctrl: Convert ctrlgrp & mongrp to pointers

The struct resctrl_val_param has control and monitor groups as char
arrays but they are not supposed to be mutated within resctrl_val().

Convert the ctrlgrp and mongrp char array within resctrl_val_param to
plain const char pointers and adjust the strlen() based checks to
check NULL instead.

Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Make some strings passed to resctrlfs functions const

Control group, monitor group and resctrl_val are not mutated and
should not be mutated within resctrlfs.c functions.

Mark th

selftests/resctrl: Make some strings passed to resctrlfs functions const

Control group, monitor group and resctrl_val are not mutated and
should not be mutated within resctrlfs.c functions.

Mark this by using const char * for the arguments.

Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Simplify bandwidth report type handling

bw_report is only needed for selecting the correct value from the
values IMC measured. It is a member in the resctrl_val_param struct and
i

selftests/resctrl: Simplify bandwidth report type handling

bw_report is only needed for selecting the correct value from the
values IMC measured. It is a member in the resctrl_val_param struct and
is always set to "reads". The value is then checked in resctrl_val()
using validate_bw_report_request() that besides validating the input,
assumes it can mutate the string which is questionable programming
practice.

Simplify handling bw_report:

- Convert validate_bw_report_request() into get_bw_report_type() that
inputs and returns const char *. Use NULL to indicate error.

- Validate the report types inside measure_mem_bw(), not in
resctrl_val().

- Pass bw_report to measure_mem_bw() from ->measure() hook because
resctrl_val() no longer needs bw_report for anything.

Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Use correct type for pids

A few functions receive PIDs through int arguments. PIDs variables
should be of type pid_t, not int.

Convert pid arguments from int to pid_t.

Before pr

selftests/resctrl: Use correct type for pids

A few functions receive PIDs through int arguments. PIDs variables
should be of type pid_t, not int.

Convert pid arguments from int to pid_t.

Before printing PID, match the type to %d by casting to int which is
enough for Linux (standard would allow using a longer integer type but
generalizing for that would complicate the code unnecessarily, the
selftest code does not need to be portable).

Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Make "bandwidth" consistent in comments & prints

Resctrl selftests refer to "bandwidth" currently in two other forms in
the code ("B/W" and "band width").

Use "bandwidth" consist

selftests/resctrl: Make "bandwidth" consistent in comments & prints

Resctrl selftests refer to "bandwidth" currently in two other forms in
the code ("B/W" and "band width").

Use "bandwidth" consistently everywhere. While at it, fix also one
"over flow" -> "overflow" on a line that is touched by the change.

Suggested-by: Reinette Chatre <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Tested-by: Babu Moger <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Add resource_info_file_exists()

Feature checking done by resctrl_mon_feature_exists() covers features
represented by the feature name presence inside the 'mon_features' file
in /s

selftests/resctrl: Add resource_info_file_exists()

Feature checking done by resctrl_mon_feature_exists() covers features
represented by the feature name presence inside the 'mon_features' file
in /sys/fs/resctrl/info/L3_MON directory. There exists a different way
to represent feature support and that is by the presence of 0 or 1 in a
single file in the info/resource directory. In this case the filename
represents what feature support is being indicated.

Add a generic function to check file presence in the
/sys/fs/resctrl/info/<RESOURCE> directory.

Signed-off-by: Maciej Wieczor-Retman <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Split validate_resctrl_feature_request()

validate_resctrl_feature_request() is used to test both if a resource is
present in the info directory, and if a passed monitoring feature

selftests/resctrl: Split validate_resctrl_feature_request()

validate_resctrl_feature_request() is used to test both if a resource is
present in the info directory, and if a passed monitoring feature is
present in the mon_features file.

Refactor validate_resctrl_feature_request() into two smaller functions
that each accomplish one check to give feature checking more
granularity:
- Resource directory presence in the /sys/fs/resctrl/info directory.
- Feature name presence in the /sys/fs/resctrl/info/<RESOURCE>/mon_features
file.

Signed-off-by: Maciej Wieczor-Retman <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Add a helper for the non-contiguous test

The CAT non-contiguous selftests have to read the file responsible for
reporting support of non-contiguous CBMs in kernel (resctrl). Then

selftests/resctrl: Add a helper for the non-contiguous test

The CAT non-contiguous selftests have to read the file responsible for
reporting support of non-contiguous CBMs in kernel (resctrl). Then the
test compares if that information matches what is reported by CPUID
output.

Add a generic helper function to read an unsigned number from
/sys/fs/resctrl/info/<RESOURCE>/<FILE>.

Signed-off-by: Maciej Wieczor-Retman <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Get domain id from cache id

Domain id is acquired differently depending on CPU. AMD tests use id
from L3 cache, whereas CPUs from other vendors base the id on topology
package id.

selftests/resctrl: Get domain id from cache id

Domain id is acquired differently depending on CPU. AMD tests use id
from L3 cache, whereas CPUs from other vendors base the id on topology
package id. In order to support L2 CAT test, this has to be
generalized.

The driver side code seems to get the domain ids from cache ids so the
approach used by the AMD branch seems to match the kernel-side code. It
will also work with L2 domain IDs as long as the cache level is
generalized.

Using the topology id was always fragile due to mismatch with the
kernel-side way to acquire the domain id. It got incorrect domain id,
e.g., when Cluster-on-Die (CoD) is enabled for CPU (but CoD is not well
suited for resctrl in the first place so it has not been a big issue if
tests don't work correctly with it).

Taking all the above into account, generalize acquiring the domain id
by taking it from the cache id and do not hard-code the cache level.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Rename resource ID to domain ID

Kernel-side calls the instances of a resource domains.

Change the resource_id naming in the selftest code to domain_id to
match the kernel side be

selftests/resctrl: Rename resource ID to domain ID

Kernel-side calls the instances of a resource domains.

Change the resource_id naming in the selftest code to domain_id to
match the kernel side better.

Suggested-by: Maciej Wieczór-Retman <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Add helper to convert L2/3 to integer

"L2"/"L3" conversion to integer is embedded into get_cache_size()
which prevents reuse.

Create a helper for the cache string to integer conv

selftests/resctrl: Add helper to convert L2/3 to integer

"L2"/"L3" conversion to integer is embedded into get_cache_size()
which prevents reuse.

Create a helper for the cache string to integer conversion to make
it reusable.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Pass write_schemata() resource instead of test name

write_schemata() takes the test name as an argument and determines the
relevant resource based on the test name. Such mapping f

selftests/resctrl: Pass write_schemata() resource instead of test name

write_schemata() takes the test name as an argument and determines the
relevant resource based on the test name. Such mapping from name to
resource does not really belong to resctrlfs.c that should provide
only generic, test-independent functions.

Pass the resource stored in the test information structure to
write_schemata() instead of the test name. The new API is also more
flexible as it enables to use write_schemata() for more than one
resource within a test.

While touching the sprintf(), move the unnecessary %c that is always
'=' directly into the format string.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Introduce generalized test framework

Each test currently has a "run test" function in per test file and
another resctrl_tests.c. The functions in resctrl_tests.c are almost
identi

selftests/resctrl: Introduce generalized test framework

Each test currently has a "run test" function in per test file and
another resctrl_tests.c. The functions in resctrl_tests.c are almost
identical.

Generalize the one in resctrl_tests.c such that it can be shared
between all of the tests. It makes adding new tests easier and removes
the per test if () forests.

Also add comment to CPU vendor IDs that they must be defined as bits
for a bitmask.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Restore the CPU affinity after CAT test

CAT test does not reset the CPU affinity after the benchmark.
This is relatively harmless as is because CAT test is the last
benchmark to r

selftests/resctrl: Restore the CPU affinity after CAT test

CAT test does not reset the CPU affinity after the benchmark.
This is relatively harmless as is because CAT test is the last
benchmark to run, however, more tests may be added later.

Store the CPU affinity the first time taskset_benchmark() is run and
add taskset_restore() which the test can call to reset the CPU mask to
its original value.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Rewrite Cache Allocation Technology (CAT) test

CAT test spawns two processes into two different control groups with
exclusive schemata. Both the processes alloc a buffer from memo

selftests/resctrl: Rewrite Cache Allocation Technology (CAT) test

CAT test spawns two processes into two different control groups with
exclusive schemata. Both the processes alloc a buffer from memory
matching their allocated LLC block size and flush the entire buffer out
of caches. Since the processes are reading through the buffer only once
during the measurement and initially all the buffer was flushed, the
test isn't testing CAT.

Rewrite the CAT test to allocate a buffer sized to half of LLC. Then
perform a sequence of tests with different LLC alloc sizes starting
from half of the CBM bits down to 1-bit CBM. Flush the buffer before
each test and read the buffer twice. Observe the LLC misses on the
second read through the buffer. As the allocated LLC block gets smaller
and smaller, the LLC misses will become larger and larger giving a
strong signal on CAT working properly.

The new CAT test is using only a single process because it relies on
measured effect against another run of itself rather than another
process adding noise. The rest of the system is set to use the CBM bits
not used by the CAT test to keep the test isolated.

Replace count_bits() with count_contiguous_bits() to get the first bit
position in order to be able to calculate masks based on it.

This change has been tested with a number of systems from different
generations.

Suggested-by: Reinette Chatre <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Exclude shareable bits from schemata in CAT test

CAT test doesn't take shareable bits into account, i.e., the test might
be sharing cache with some devices (e.g., graphics).

Intr

selftests/resctrl: Exclude shareable bits from schemata in CAT test

CAT test doesn't take shareable bits into account, i.e., the test might
be sharing cache with some devices (e.g., graphics).

Introduce get_mask_no_shareable() and use it to provision an
environment for CAT test where the allocated LLC is isolated better.
Excluding shareable_bits may create hole(s) into the cbm_mask, thus add
a new helper count_contiguous_bits() to find the longest contiguous set
of CBM bits.

create_bit_mask() is needed by an upcoming CAT test rewrite so make it
available in resctrl.h right away.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Mark get_cache_size() cache_type const

get_cache_size() does not modify cache_type so it could be const.

Mark cache_type const so that const char * can be passed to it. This
prev

selftests/resctrl: Mark get_cache_size() cache_type const

get_cache_size() does not modify cache_type so it could be const.

Mark cache_type const so that const char * can be passed to it. This
prevents warnings once many of the test parameters are marked const.

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Refactor get_cbm_mask() and rename to get_full_cbm()

Callers of get_cbm_mask() are required to pass a string into which the
capacity bitmask (CBM) is read. Neither CAT nor CMT tes

selftests/resctrl: Refactor get_cbm_mask() and rename to get_full_cbm()

Callers of get_cbm_mask() are required to pass a string into which the
capacity bitmask (CBM) is read. Neither CAT nor CMT tests need the
bitmask as string but just convert it into an unsigned long value.

Another limitation is that the bit mask reader can only read
.../cbm_mask files.

Generalize the bit mask reading function into get_bit_mask() such that
it can be used to handle other files besides the .../cbm_mask and
handles the unsigned long conversion within get_bit_mask() using
fscanf(). Change get_cbm_mask() to use get_bit_mask() and rename it to
get_full_cbm() to better indicate what the function does.

Return error from get_full_cbm() if the bitmask is zero for some reason
because it makes the code more robust as the selftests naturally assume
the bitmask has some bits.

Also mark cache_type const while at it and remove useless comments that
are related to processing of CBM bits.

Co-developed-by: Fenghua Yu <[email protected]>
Signed-off-by: Fenghua Yu <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Change function comments to say < 0 on error

A number function comments state the function return non-zero on
failure but in reality they can only return 0 on success and < 0 on
e

selftests/resctrl: Change function comments to say < 0 on error

A number function comments state the function return non-zero on
failure but in reality they can only return 0 on success and < 0 on
error.

Update the comments to say < 0 on error to match the behavior.

While at it, improve cat_val() comment to state that 0 means the test
was run (either pass or fail).

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests/resctrl: Return -1 instead of errno on error

A number of functions in the resctrl selftests return errno. It is
problematic because errno is positive which is often counterintuitive.
Also,

selftests/resctrl: Return -1 instead of errno on error

A number of functions in the resctrl selftests return errno. It is
problematic because errno is positive which is often counterintuitive.
Also, every site returning errno prints the error message already with
ksft_perror() so there is not much added value in returning the precise
error code.

Simply convert all places returning errno to return -1 that is typical
userspace error code in case of failures.

While at it, improve resctrl_val() comment to state that 0 means the
test was run (either pass or fail).

Signed-off-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

show more ...