Changes from v1 (https://lore.kernel.org/damon/20231212191206.52917-1-sj@kernel.org/) - Fix conflicts on latest mm-unstable tree
Changes from RFC (https://lore.kernel.org/damon/20231202000806.46210-1-sj@kernel.org/) - Make the working set size estimation test more reliable - Wordsmith coverletter and commit messages - Rename _damon.py to _damon_sysfs.py
DAMON exports most of its functionality via its sysfs interface. Hence most DAMON functionality tests could be implemented using the interface. However, because the interfaces require simple but multiple operations for many controls, writing all such tests from the scratch could be repetitive and time consuming.
Implement a minimum DAMON sysfs control module, and a couple of DAMON functionality tests using the control module. The first test is for ensuring minimum accuracy of data access monitoring, and the second test is for finding if a previously found and fixed bug is introduced again.
Note that the DAMON sysfs control module is only for avoiding duplicating code in tests. For convenient and general control of DAMON, users should use DAMON user-space tools that developed for the purpose, such as damo[1].
[1] https://github.com/damonitor/damo
Patches Sequence ----------------
This patchset is constructed with five patches. The first three patches implement a Python-written test implementation-purpose DAMON sysfs control module. The implementation is incrementally done in the sequence of the basic data structure (first patch) first, kdamonds start command (second patch) next, and finally DAMOS tried bytes update command (third patch).
Then two patches for implementing selftests using the module follows. The fourth patch implements a basic functionality test of DAMON for working set estimation accuracy. Finally, the fifth patch implements a corner case test for a previously found bug.
SeongJae Park (5): selftests/damon: implement a python module for test-purpose DAMON sysfs controls selftests/damon/_damon_sysfs: implement kdamonds start function selftests/damon/_damon_sysfs: implement updat_schemes_tried_bytes command selftests/damon: add a test for update_schemes_tried_regions sysfs command selftests/damon: add a test for update_schemes_tried_regions hang bug
tools/testing/selftests/damon/Makefile | 3 + tools/testing/selftests/damon/_damon_sysfs.py | 322 ++++++++++++++++++ tools/testing/selftests/damon/access_memory.c | 41 +++ ...sysfs_update_schemes_tried_regions_hang.py | 33 ++ ...te_schemes_tried_regions_wss_estimation.py | 55 +++ 5 files changed, 454 insertions(+) create mode 100644 tools/testing/selftests/damon/_damon_sysfs.py create mode 100644 tools/testing/selftests/damon/access_memory.c create mode 100755 tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py create mode 100755 tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py
base-commit: 091b8c820de390a6235595bdb281edab63b9befe
Implement a python module for DAMON sysfs controls. The module is aimed to be useful for writing DAMON functionality tests in future. Nonetheless, this module is only representing a subset of DAMON sysfs files. Following commits will implement more DAMON sysfs controls.
Signed-off-by: SeongJae Park sj@kernel.org --- tools/testing/selftests/damon/_damon_sysfs.py | 102 ++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 tools/testing/selftests/damon/_damon_sysfs.py
diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/selftests/damon/_damon_sysfs.py new file mode 100644 index 000000000000..78101846ab66 --- /dev/null +++ b/tools/testing/selftests/damon/_damon_sysfs.py @@ -0,0 +1,102 @@ +# SPDX-License-Identifier: GPL-2.0 + +class DamosAccessPattern: + size = None + nr_accesses = None + age = None + scheme = None + + def __init__(self, size=None, nr_accesses=None, age=None): + self.size = size + self.nr_accesses = nr_accesses + self.age = age + + if self.size == None: + self.size = [0, 2**64 - 1] + if self.nr_accesses == None: + self.nr_accesses = [0, 2**64 - 1] + if self.age == None: + self.age = [0, 2**64 - 1] + +class Damos: + action = None + access_pattern = None + # todo: Support quotas, watermarks, stats, tried_regions + idx = None + context = None + + def __init__(self, action='stat', access_pattern=DamosAccessPattern()): + self.action = action + self.access_pattern = access_pattern + self.access_pattern.scheme = self + +class DamonTarget: + pid = None + # todo: Support target regions if test is made + idx = None + context = None + + def __init__(self, pid): + self.pid = pid + +class DamonAttrs: + sample_us = None + aggr_us = None + update_us = None + min_nr_regions = None + max_nr_regions = None + context = None + + def __init__(self, sample_us=5000, aggr_us=100000, update_us=1000000, + min_nr_regions=10, max_nr_regions=1000): + self.sample_us = sample_us + self.aggr_us = aggr_us + self.update_us = update_us + self.min_nr_regions = min_nr_regions + self.max_nr_regions = max_nr_regions + +class DamonCtx: + ops = None + monitoring_attrs = None + targets = None + schemes = None + kdamond = None + idx = None + + def __init__(self, ops='paddr', monitoring_attrs=DamonAttrs(), targets=[], + schemes=[]): + self.ops = ops + self.monitoring_attrs = monitoring_attrs + self.monitoring_attrs.context = self + + self.targets = targets + for idx, target in enumerate(self.targets): + target.idx = idx + target.context = self + + self.schemes = schemes + for idx, scheme in enumerate(self.schemes): + scheme.idx = idx + scheme.context = self + +class Kdamond: + state = None + pid = None + contexts = None + idx = None # index of this kdamond between siblings + kdamonds = None # parent + + def __init__(self, contexts=[]): + self.contexts = contexts + for idx, context in enumerate(self.contexts): + context.idx = idx + context.kdamond = self + +class Kdamonds: + kdamonds = [] + + def __init__(self, kdamonds=[]): + self.kdamonds = kdamonds + for idx, kdamond in enumerate(self.kdamonds): + kdamond.idx = idx + kdamond.kdamonds = self
Extend the tests-writing-purpose DAMON sysfs control module to support the kdamonds start functionality.
Signed-off-by: SeongJae Park sj@kernel.org --- tools/testing/selftests/damon/_damon_sysfs.py | 206 ++++++++++++++++++ 1 file changed, 206 insertions(+)
diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/selftests/damon/_damon_sysfs.py index 78101846ab66..6b99f87a5f1e 100644 --- a/tools/testing/selftests/damon/_damon_sysfs.py +++ b/tools/testing/selftests/damon/_damon_sysfs.py @@ -1,5 +1,28 @@ # SPDX-License-Identifier: GPL-2.0
+import os + +sysfs_root = '/sys/kernel/mm/damon/admin' + +def write_file(path, string): + "Returns error string if failed, or None otherwise" + string = '%s' % string + try: + with open(path, 'w') as f: + f.write(string) + except Exception as e: + return '%s' % e + return None + +def read_file(path): + '''Returns the read content and error string. The read content is None if + the reading failed''' + try: + with open(path, 'r') as f: + return f.read(), None + except Exception as e: + return None, '%s' % e + class DamosAccessPattern: size = None nr_accesses = None @@ -18,6 +41,35 @@ class DamosAccessPattern: if self.age == None: self.age = [0, 2**64 - 1]
+ def sysfs_dir(self): + return os.path.join(self.scheme.sysfs_dir(), 'access_pattern') + + def stage(self): + err = write_file( + os.path.join(self.sysfs_dir(), 'sz', 'min'), self.size[0]) + if err != None: + return err + err = write_file( + os.path.join(self.sysfs_dir(), 'sz', 'max'), self.size[1]) + if err != None: + return err + err = write_file(os.path.join(self.sysfs_dir(), 'nr_accesses', 'min'), + self.nr_accesses[0]) + if err != None: + return err + err = write_file(os.path.join(self.sysfs_dir(), 'nr_accesses', 'max'), + self.nr_accesses[1]) + if err != None: + return err + err = write_file( + os.path.join(self.sysfs_dir(), 'age', 'min'), self.age[0]) + if err != None: + return err + err = write_file( + os.path.join(self.sysfs_dir(), 'age', 'max'), self.age[1]) + if err != None: + return err + class Damos: action = None access_pattern = None @@ -30,6 +82,39 @@ class Damos: self.access_pattern = access_pattern self.access_pattern.scheme = self
+ def sysfs_dir(self): + return os.path.join( + self.context.sysfs_dir(), 'schemes', '%d' % self.idx) + + def stage(self): + err = write_file(os.path.join(self.sysfs_dir(), 'action'), self.action) + if err != None: + return err + err = self.access_pattern.stage() + if err != None: + return err + + # disable quotas + err = write_file(os.path.join(self.sysfs_dir(), 'quotas', 'ms'), '0') + if err != None: + return err + err = write_file( + os.path.join(self.sysfs_dir(), 'quotas', 'bytes'), '0') + if err != None: + return err + + # disable watermarks + err = write_file( + os.path.join(self.sysfs_dir(), 'watermarks', 'metric'), 'none') + if err != None: + return err + + # disable filters + err = write_file( + os.path.join(self.sysfs_dir(), 'filters', 'nr_filters'), '0') + if err != None: + return err + class DamonTarget: pid = None # todo: Support target regions if test is made @@ -39,6 +124,18 @@ class DamonTarget: def __init__(self, pid): self.pid = pid
+ def sysfs_dir(self): + return os.path.join( + self.context.sysfs_dir(), 'targets', '%d' % self.idx) + + def stage(self): + err = write_file( + os.path.join(self.sysfs_dir(), 'regions', 'nr_regions'), '0') + if err != None: + return err + return write_file( + os.path.join(self.sysfs_dir(), 'pid_target'), self.pid) + class DamonAttrs: sample_us = None aggr_us = None @@ -55,6 +152,40 @@ class DamonAttrs: self.min_nr_regions = min_nr_regions self.max_nr_regions = max_nr_regions
+ def interval_sysfs_dir(self): + return os.path.join(self.context.sysfs_dir(), 'monitoring_attrs', + 'intervals') + + def nr_regions_range_sysfs_dir(self): + return os.path.join(self.context.sysfs_dir(), 'monitoring_attrs', + 'nr_regions') + + def stage(self): + err = write_file(os.path.join(self.interval_sysfs_dir(), 'sample_us'), + self.sample_us) + if err != None: + return err + err = write_file(os.path.join(self.interval_sysfs_dir(), 'aggr_us'), + self.aggr_us) + if err != None: + return err + err = write_file(os.path.join(self.interval_sysfs_dir(), 'update_us'), + self.update_us) + if err != None: + return err + + err = write_file( + os.path.join(self.nr_regions_range_sysfs_dir(), 'min'), + self.min_nr_regions) + if err != None: + return err + + err = write_file( + os.path.join(self.nr_regions_range_sysfs_dir(), 'max'), + self.max_nr_regions) + if err != None: + return err + class DamonCtx: ops = None monitoring_attrs = None @@ -79,6 +210,46 @@ class DamonCtx: scheme.idx = idx scheme.context = self
+ def sysfs_dir(self): + return os.path.join(self.kdamond.sysfs_dir(), 'contexts', + '%d' % self.idx) + + def stage(self): + err = write_file( + os.path.join(self.sysfs_dir(), 'operations'), self.ops) + if err != None: + return err + err = self.monitoring_attrs.stage() + if err != None: + return err + + nr_targets_file = os.path.join( + self.sysfs_dir(), 'targets', 'nr_targets') + content, err = read_file(nr_targets_file) + if err != None: + return err + if int(content) != len(self.targets): + err = write_file(nr_targets_file, '%d' % len(self.targets)) + if err != None: + return err + for target in self.targets: + err = target.stage() + if err != None: + return err + + nr_schemes_file = os.path.join( + self.sysfs_dir(), 'schemes', 'nr_schemes') + content, err = read_file(nr_schemes_file) + if int(content) != len(self.schemes): + err = write_file(nr_schemes_file, '%d' % len(self.schemes)) + if err != None: + return err + for scheme in self.schemes: + err = scheme.stage() + if err != None: + return err + return None + class Kdamond: state = None pid = None @@ -92,6 +263,27 @@ class Kdamond: context.idx = idx context.kdamond = self
+ def sysfs_dir(self): + return os.path.join(self.kdamonds.sysfs_dir(), '%d' % self.idx) + + def start(self): + nr_contexts_file = os.path.join(self.sysfs_dir(), + 'contexts', 'nr_contexts') + content, err = read_file(nr_contexts_file) + if err != None: + return err + if int(content) != len(self.contexts): + err = write_file(nr_contexts_file, '%d' % len(self.contexts)) + if err != None: + return err + + for context in self.contexts: + err = context.stage() + if err != None: + return err + err = write_file(os.path.join(self.sysfs_dir(), 'state'), 'on') + return err + class Kdamonds: kdamonds = []
@@ -100,3 +292,17 @@ class Kdamonds: for idx, kdamond in enumerate(self.kdamonds): kdamond.idx = idx kdamond.kdamonds = self + + def sysfs_dir(self): + return os.path.join(sysfs_root, 'kdamonds') + + def start(self): + err = write_file(os.path.join(self.sysfs_dir(), 'nr_kdamonds'), + '%s' % len(self.kdamonds)) + if err != None: + return err + for kdamond in self.kdamonds: + err = kdamond.start() + if err != None: + return err + return None
Implement update_schemes_tried_bytes command of DAMON sysfs interface in _damon_sysfs.py. It is not only making the update, but also read the updated value from the sysfs interface and store it in the Kdamond python objects so that the user of the module can easily get the value.
Signed-off-by: SeongJae Park sj@kernel.org --- tools/testing/selftests/damon/_damon_sysfs.py | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/selftests/damon/_damon_sysfs.py index 6b99f87a5f1e..e98cf4b6a4b7 100644 --- a/tools/testing/selftests/damon/_damon_sysfs.py +++ b/tools/testing/selftests/damon/_damon_sysfs.py @@ -76,6 +76,7 @@ class Damos: # todo: Support quotas, watermarks, stats, tried_regions idx = None context = None + tried_bytes = None
def __init__(self, action='stat', access_pattern=DamosAccessPattern()): self.action = action @@ -284,6 +285,19 @@ class Kdamond: err = write_file(os.path.join(self.sysfs_dir(), 'state'), 'on') return err
+ def update_schemes_tried_bytes(self): + err = write_file(os.path.join(self.sysfs_dir(), 'state'), + 'update_schemes_tried_bytes') + if err != None: + return err + for context in self.contexts: + for scheme in context.schemes: + content, err = read_file(os.path.join(scheme.sysfs_dir(), + 'tried_regions', 'total_bytes')) + if err != None: + return err + scheme.tried_bytes = int(content) + class Kdamonds: kdamonds = []
Add a selftest for verifying the accuracy of DAMON's access monitoring functionality. The test starts a program of artificial access pattern, monitor the access pattern using DAMON, and check if DAMON finds expected amount of hot data region (working set size) with only acceptable error rate.
Note that the acceptable error rate is set with only naive assumptions and small number of tests. Hence failures of the test may not always mean DAMON is broken. Rather than that, those could be a signal to better understand the real accuracy level of DAMON in wider environments. Based on further finding, we could optimize DAMON or adjust the expectation of the test.
Signed-off-by: SeongJae Park sj@kernel.org --- tools/testing/selftests/damon/Makefile | 2 + tools/testing/selftests/damon/access_memory.c | 41 ++++++++++++++ ...te_schemes_tried_regions_wss_estimation.py | 55 +++++++++++++++++++ 3 files changed, 98 insertions(+) create mode 100644 tools/testing/selftests/damon/access_memory.c create mode 100755 tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py
diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile index b71247ba7196..90ffafc42c5e 100644 --- a/tools/testing/selftests/damon/Makefile +++ b/tools/testing/selftests/damon/Makefile @@ -2,6 +2,7 @@ # Makefile for damon selftests
TEST_GEN_FILES += huge_count_read_write +TEST_GEN_FILES += access_memory
TEST_FILES = _chk_dependency.sh _debugfs_common.sh TEST_PROGS = debugfs_attrs.sh debugfs_schemes.sh debugfs_target_ids.sh @@ -9,6 +10,7 @@ TEST_PROGS += debugfs_empty_targets.sh debugfs_huge_count_read_write.sh TEST_PROGS += debugfs_duplicate_context_creation.sh TEST_PROGS += debugfs_rm_non_contexts.sh TEST_PROGS += sysfs.sh sysfs_update_removed_scheme_dir.sh +TEST_PROGS += sysfs_update_schemes_tried_regions_wss_estimation.py TEST_PROGS += reclaim.sh lru_sort.sh
include ../lib.mk diff --git a/tools/testing/selftests/damon/access_memory.c b/tools/testing/selftests/damon/access_memory.c new file mode 100644 index 000000000000..585a2fa54329 --- /dev/null +++ b/tools/testing/selftests/damon/access_memory.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Artificial memory access program for testing DAMON. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +int main(int argc, char *argv[]) +{ + char **regions; + clock_t start_clock; + int nr_regions; + int sz_region; + int access_time_ms; + int i; + + if (argc != 4) { + printf("Usage: %s <number> <size (bytes)> <time (ms)>\n", + argv[0]); + return -1; + } + + nr_regions = atoi(argv[1]); + sz_region = atoi(argv[2]); + access_time_ms = atoi(argv[3]); + + regions = malloc(sizeof(*regions) * nr_regions); + for (i = 0; i < nr_regions; i++) + regions[i] = malloc(sz_region); + + for (i = 0; i < nr_regions; i++) { + start_clock = clock(); + while ((clock() - start_clock) * 1000 / CLOCKS_PER_SEC < + access_time_ms) + memset(regions[i], i, 1024 * 1024 * 10); + } + return 0; +} diff --git a/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py new file mode 100755 index 000000000000..cdbf19b442c9 --- /dev/null +++ b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py @@ -0,0 +1,55 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 + +import subprocess +import time + +import _damon_sysfs + +def main(): + # access two 10 MiB memory regions, 2 second per each + sz_region = 10 * 1024 * 1024 + proc = subprocess.Popen(['./access_memory', '2', '%d' % sz_region, '2000']) + kdamonds = _damon_sysfs.Kdamonds([_damon_sysfs.Kdamond( + contexts=[_damon_sysfs.DamonCtx( + ops='vaddr', + targets=[_damon_sysfs.DamonTarget(pid=proc.pid)], + schemes=[_damon_sysfs.Damos( + access_pattern=_damon_sysfs.DamosAccessPattern( + # >= 25% access rate, >= 200ms age + nr_accesses=[5, 20], age=[2, 2**64 - 1]))] # schemes + )] # contexts + )]) # kdamonds + + err = kdamonds.start() + if err != None: + print('kdmaond start failed: %s' % err) + exit(1) + + wss_collected = [] + while proc.poll() == None: + time.sleep(0.1) + err = kdamonds.kdamonds[0].update_schemes_tried_bytes() + if err != None: + print('tried bytes update failed: %s' % err) + exit(1) + + wss_collected.append( + kdamonds.kdamonds[0].contexts[0].schemes[0].tried_bytes) + + wss_collected.sort() + acceptable_error_rate = 0.2 + for percentile in [50, 75]: + sample = wss_collected[int(len(wss_collected) * percentile / 100)] + error_rate = abs(sample - sz_region) / sz_region + print('%d-th percentile (%d) error %f' % + (percentile, sample, error_rate)) + if error_rate > acceptable_error_rate: + print('the error rate is not acceptable (> %f)' % + acceptable_error_rate) + print('samples are as below') + print('\n'.join(['%d' % wss for wss in wss_collected])) + exit(1) + +if __name__ == '__main__': + main()
Add a test for reproducing the update_schemes_tried_{regions,bytes} command-causing indefinite hang bug that fixed by commit 7d6fa31a2fd7 ("mm/damon/sysfs-schemes: add timeout for update_schemes_tried_regions"), to avoid mistakenly re-introducing the bug. Refer to the fix commit for more details of the bug.
Signed-off-by: SeongJae Park sj@kernel.org --- tools/testing/selftests/damon/Makefile | 1 + ...sysfs_update_schemes_tried_regions_hang.py | 33 +++++++++++++++++++ 2 files changed, 34 insertions(+) create mode 100755 tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py
diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile index 90ffafc42c5e..8a1cc2bf1864 100644 --- a/tools/testing/selftests/damon/Makefile +++ b/tools/testing/selftests/damon/Makefile @@ -10,6 +10,7 @@ TEST_PROGS += debugfs_empty_targets.sh debugfs_huge_count_read_write.sh TEST_PROGS += debugfs_duplicate_context_creation.sh TEST_PROGS += debugfs_rm_non_contexts.sh TEST_PROGS += sysfs.sh sysfs_update_removed_scheme_dir.sh +TEST_PROGS += sysfs_update_schemes_tried_regions_hang.py TEST_PROGS += sysfs_update_schemes_tried_regions_wss_estimation.py TEST_PROGS += reclaim.sh lru_sort.sh
diff --git a/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py new file mode 100755 index 000000000000..8c690ba1a573 --- /dev/null +++ b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py @@ -0,0 +1,33 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 + +import subprocess +import time + +import _damon_sysfs + +def main(): + proc = subprocess.Popen(['sleep', '2']) + kdamonds = _damon_sysfs.Kdamonds([_damon_sysfs.Kdamond( + contexts=[_damon_sysfs.DamonCtx( + ops='vaddr', + targets=[_damon_sysfs.DamonTarget(pid=proc.pid)], + schemes=[_damon_sysfs.Damos( + access_pattern=_damon_sysfs.DamosAccessPattern( + nr_accesses=[200, 200]))] # schemes + )] # contexts + )]) # kdamonds + + err = kdamonds.start() + if err != None: + print('kdmaond start failed: %s' % err) + exit(1) + + while proc.poll() == None: + err = kdamonds.kdamonds[0].update_schemes_tried_bytes() + if err != None: + print('tried bytes update failed: %s' % err) + exit(1) + +if __name__ == '__main__': + main()
linux-kselftest-mirror@lists.linaro.org
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SeongJae Park