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Message-ID: <68e2a732-3016-a8a6-3f16-3c9ea1a0f9f6@intel.com>
Date: Thu, 14 Sep 2023 10:29:54 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: Shuah Khan <shuah@...nel.org>,
Shuah Khan <skhan@...uxfoundation.org>,
<linux-kselftest@...r.kernel.org>,
Maciej Wieczór-Retman
<maciej.wieczor-retman@...el.com>,
LKML <linux-kernel@...r.kernel.org>,
Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
<stable@...r.kernel.org>
Subject: Re: [PATCH 1/5] selftests/resctrl: Extend signal handler coverage to
unmount on receiving signal
Hi Ilpo,
On 9/14/2023 10:05 AM, Ilpo Järvinen wrote:
> On Thu, 14 Sep 2023, Reinette Chatre wrote:
>> On 9/14/2023 3:16 AM, Ilpo Järvinen wrote:
>>> On Wed, 13 Sep 2023, Reinette Chatre wrote:
>>>> On 9/13/2023 3:01 AM, Ilpo Järvinen wrote:
>>>>> On Tue, 12 Sep 2023, Reinette Chatre wrote:
>>>>>> On 9/11/2023 4:19 AM, Ilpo Järvinen wrote:
>>>>>>> Unmounting resctrl FS has been moved into the per test functions in
>>>>>>> resctrl_tests.c by commit caddc0fbe495 ("selftests/resctrl: Move
>>>>>>> resctrl FS mount/umount to higher level"). In case a signal (SIGINT,
>>>>>>> SIGTERM, or SIGHUP) is received, the running selftest is aborted by
>>>>>>> ctrlc_handler() which then unmounts resctrl fs before exiting. The
>>>>>>> current section between signal_handler_register() and
>>>>>>> signal_handler_unregister(), however, does not cover the entire
>>>>>>> duration when resctrl FS is mounted.
>>>>>>>
>>>>>>> Move signal_handler_register() and signal_handler_unregister() call
>>>>>>> into the test functions in resctrl_tests.c to properly unmount resctrl
>>>>>>> fs. Adjust child process kill() call in ctrlc_handler() to only be
>>>>>>> invoked if the child was already forked.
>>>>>>
>>>>>> Thank you for catching this.
>>>>>>
>>>>>>>
>>>>>>> Fixes: caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level")
>>>>>>> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
>>>>>>> Cc: <stable@...r.kernel.org>
>>>>>>> ---
>>>>>>> tools/testing/selftests/resctrl/cat_test.c | 8 -------
>>>>>>> .../testing/selftests/resctrl/resctrl_tests.c | 24 +++++++++++++++++++
>>>>>>> tools/testing/selftests/resctrl/resctrl_val.c | 22 ++++++++---------
>>>>>>> 3 files changed, 34 insertions(+), 20 deletions(-)
>>>>>>>
>>>>>>> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
>>>>>>> index 97b87285ab2a..224ba8544d8a 100644
>>>>>>> --- a/tools/testing/selftests/resctrl/cat_test.c
>>>>>>> +++ b/tools/testing/selftests/resctrl/cat_test.c
>>>>>>> @@ -167,12 +167,6 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
>>>>>>> strcpy(param.filename, RESULT_FILE_NAME1);
>>>>>>> param.num_of_runs = 0;
>>>>>>> param.cpu_no = sibling_cpu_no;
>>>>>>> - } else {
>>>>>>> - ret = signal_handler_register();
>>>>>>> - if (ret) {
>>>>>>> - kill(bm_pid, SIGKILL);
>>>>>>> - goto out;
>>>>>>> - }
>>>>>>> }
>>>>>>>
>>>>>>> remove(param.filename);
>>>>>>> @@ -209,10 +203,8 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
>>>>>>> }
>>>>>>> close(pipefd[0]);
>>>>>>> kill(bm_pid, SIGKILL);
>>>>>>> - signal_handler_unregister();
>>>>>>> }
>>>>>>>
>>>>>>> -out:
>>>>>>> cat_test_cleanup();
>>>>>>>
>>>>>>> return ret;
>>>>>>> diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
>>>>>>> index 823672a20a43..3d66fbdc2df3 100644
>>>>>>> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
>>>>>>> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
>>>>>>> @@ -73,8 +73,13 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
>>>>>>>
>>>>>>> ksft_print_msg("Starting MBM BW change ...\n");
>>>>>>>
>>>>>>> + res = signal_handler_register();
>>>>>>> + if (res)
>>>>>>> + return;
>>>>>>> +
>>>>>>> res = mount_resctrlfs();
>>>>>>> if (res) {
>>>>>>> + signal_handler_unregister();
>>>>>>> ksft_exit_fail_msg("Failed to mount resctrl FS\n");
>>>>>>> return;
>>>>>>> }
>>>>>>> @@ -91,6 +96,7 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
>>>>>>>
>>>>>>> umount:
>>>>>>> umount_resctrlfs();
>>>>>>> + signal_handler_unregister();
>>>>>>> }
>>>>>>>
>>>>>>> static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>>>>>> @@ -99,8 +105,13 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>>>>>>
>>>>>>> ksft_print_msg("Starting MBA Schemata change ...\n");
>>>>>>>
>>>>>>> + res = signal_handler_register();
>>>>>>> + if (res)
>>>>>>> + return;
>>>>>>> +
>>>>>>> res = mount_resctrlfs();
>>>>>>> if (res) {
>>>>>>> + signal_handler_unregister();
>>>>>>> ksft_exit_fail_msg("Failed to mount resctrl FS\n");
>>>>>>> return;
>>>>>>> }
>>>>>>> @@ -115,6 +126,7 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>>>>>>
>>>>>>> umount:
>>>>>>> umount_resctrlfs();
>>>>>>> + signal_handler_unregister();
>>>>>>> }
>>>>>>>
>>>>>>
>>>>>> This adds more duplicated code for every test. Have you considered a
>>>>>> single test setup function that can be used to mount resctrl FS and setup
>>>>>> the signal handler paired with a single test teardown function?
>>>>>
>>>>> Yes. Consolidating all these is among my not-yet submitted patches.
>>>>> I just had to do a backport-friendly Fixes patch first for this.
>>>>>
>>>>
>>>> Could you please help me understand how the duplicate calls are more
>>>> backport friendly?
>>>
>>> Hi,
>>>
>>> It's simply because the refactoring that has to be done to be able to
>>> introduce the generalized test framework is much more invasive and far
>>> reaching than this patch. Essentially, all the call signatures of the test
>>> functions need to match and the feature checks need to be done in new per
>>> test functions too. This is the diffstat of those changes alone:
>>>
>>> tools/testing/selftests/resctrl/cat_test.c | 21 +++--
>>> tools/testing/selftests/resctrl/cmt_test.c | 26 +++--
>>> tools/testing/selftests/resctrl/mba_test.c | 20 +++-
>>> tools/testing/selftests/resctrl/mbm_test.c | 20 +++-
>>> tools/testing/selftests/resctrl/resctrl.h | 43 ++++++++-
>>> tools/testing/selftests/resctrl/resctrl_tests.c | 220 +++++++++++++++----------------------------
>>> tools/testing/selftests/resctrl/resctrlfs.c | 5 +
>>>
>>> (tools/testing/selftests/resctrl/resctrl_tests.c --- part would
>>> be slightly less if I'd reorder this patch but that only 24 lines off as
>>> per diffstat of this patch).
>>>
>>> But that's not all.... To be able to push the generalized test framework
>>> to stable, you need to also count in the benchmark cmd changes which
>>> worked towards making the call signatures identical. So here's the
>>> diffstat for that series for quick reference:
>>>
>>> tools/testing/selftests/resctrl/cache.c | 5 +-
>>> tools/testing/selftests/resctrl/cat_test.c | 13 +--
>>> tools/testing/selftests/resctrl/cmt_test.c | 34 ++++--
>>> tools/testing/selftests/resctrl/mba_test.c | 4 +-
>>> tools/testing/selftests/resctrl/mbm_test.c | 7 +-
>>> tools/testing/selftests/resctrl/resctrl.h | 16 +--
>>> .../testing/selftests/resctrl/resctrl_tests.c | 100 ++++++++----------
>>> tools/testing/selftests/resctrl/resctrl_val.c | 10 +-
>>>
>>> That's ~500 lines changed vs ~50 so it's a magnitude worse and much less
>>> localized.
>>>
>>> And rest assured, I did not like introducing the duplicated calls any more
>>> than you do (I did not write the generalized test framework for nothing,
>>> after all) but the way taken in this patch seemed the most reasonable
>>> option under these circumstances.
>>>
>>
>> hmmm ... I did not expect that a total refactoring would be needed.
>>
>> I was thinking about a change from this:
>>
>>
>> testX(...)
>> {
>>
>> res = signal_handler_register();
>> /* error handling */
>> res = mount_resctrlfs();
>> /* error handling */
>>
>> /* test */
>>
>> unmount_resctrlfs();
>> signal_handler_register();
>>
>> }
>>
>>
>> to this:
>>
>>
>> int test_setup(...)
>> {
>> res = signal_handler_register();
>> /* error handling */
>> res = mount_resctrlfs();
>> /* error handling */
>> }
>>
>>
>> void test_cleanup(...)
>> {
>> unmount_resctrlfs();
>> signal_handler_register();
>> }
>>
>>
>> testX(...)
>> {
>>
>> res = test_setup(..);
>> /* error handling */
>>
>> /* test */
>>
>> test_cleanup();
>> }
>>
>> I expect this to also support the bigger refactoring.
>
> Okay, I'll do so then.
>
> However, having already written the generic run_single_test() function
> that is part of the generic test framework, I definitely don't feel those
> helpers would be that helpful for it. It more feels like they'd make the
> flow less obvious by adding those two extra calls there but that's of
> course matter of taste.
Sounds like there is some room for improvement here, perhaps open coding
the test_setup() and test_cleanup() helpers within run_single_test().
This is purely speculation on my part as I have not seen the code.
Reinette
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