Hi Sai,
On 3/10/2020 7:46 PM, Sai Praneeth Prakhya wrote:
> On Tue, 2020-03-10 at 15:18 -0700, Reinette Chatre wrote:
>> On 3/6/2020 7:40 PM, Sai Praneeth Prakhya wrote:
>>> .mum_resctrlfs = 0,
>>> .filename = RESULT_FILE_NAME,
>>> - .mask = ~(long_mask << n) & long_mask,
>>> - .span = cache_size * n / count_of_bits,
>>> .num_of_runs = 0,
>>> - .setup = cqm_setup,
>>> + .setup = cqm_setup
>>> };
>>> + int ret;
>>> + char schemata[64];
>>> + unsigned long long_mask;
>>>
>>> - if (strcmp(benchmark_cmd[0], "fill_buf") == 0)
>>> - sprintf(benchmark_cmd[1], "%lu", param.span);
>>> + ret = remount_resctrlfs(1);
>>> + if (ret)
>>> + return ret;
>>
>> Here resctrl is remounted and followed by some changes to the root
>> group's schemata. That is followed by a call to resctrl_val that
>> attempts to remount resctrl again that will undo all the configurations
>> inbetween.
>
> No, it wouldn't because mum_resctrlfs is 0. When resctrl FS is already mounted
> and mum_resctrlfs is 0, then remount_resctrlfs() is a noop.
>
I missed that. Thank you.
fyi ... when I tried these tests I encountered the following error
related to unmounting:
[SNIP]
ok Write schema "L3:1=7fff" to resctrl FS
ok Write schema "L3:1=ffff" to resctrl FS
ok Write schema "L3:1=1ffff" to resctrl FS
ok Write schema "L3:1=3ffff" to resctrl FS
# Unable to umount resctrl: Device or resource busy
# Results are displayed in (Bytes)
ok CQM: diff within 5% for mask 1
# alloc_llc_cache_size: 2883584
# avg_llc_occu_resc: 2973696
ok CQM: diff within 5% for mask 3
[SNIP]
This seems to originate from resctrl_val() that forces an unmount but if
that fails the error is not propagated.
>>> diff --git a/tools/testing/selftests/resctrl/resctrl_val.c
>>> b/tools/testing/selftests/resctrl/resctrl_val.c
>>> index 271cb5c976f5..c59fad6cb9b0 100644
>>> --- a/tools/testing/selftests/resctrl/resctrl_val.c
>>> +++ b/tools/testing/selftests/resctrl/resctrl_val.c
>>> @@ -705,29 +705,21 @@ int resctrl_val(char **benchmark_cmd, struct
>>> resctrl_val_param *param)
>>> goto out;
>>> }
>>>
>>> - /* Give benchmark enough time to fully run */
>>> - sleep(1);
>>> -
>>> /* Test runs until the callback setup() tells the test to stop. */
>>> while (1) {
>>> + ret = param->setup(param);
>>> + if (ret) {
>>> + ret = 0;
>>> + break;
>>> + }
>>> +
>>> + /* Measure vals sleeps for a second */
>>> if ((strcmp(resctrl_val, "mbm") == 0) ||
>>> (strcmp(resctrl_val, "mba") == 0)) {
>>> - ret = param->setup(param);
>>> - if (ret) {
>>> - ret = 0;
>>> - break;
>>> - }
>>> -
(I refer to the above snippet in my comment below)
>>> ret = measure_vals(param, &bw_resc_start);
>>> if (ret)
>>> break;
>>> } else if (strcmp(resctrl_val, "cqm") == 0) {
>>> - ret = param->setup(param);
>>> - if (ret) {
>>> - ret = 0;
>>> - break;
>>> - }
>>> - sleep(1);
>>> ret = measure_cache_vals(param, bm_pid);
>>> if (ret)
>>> break;
>>
>> This change affects not just the cache monitoring test. Could this
>> change be extracted into its own patch to be clear what is done here and
>> how it impacts the other tests?
>
> This change shouldn't impact other tests (i.e. CAT) because CAT will not call
> resctrl_val().
I was referring to the snippet above that seems to impact the "mbm" and
"mba" tests by moving the call to "param->setup" for the them.
>
>>> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c
>>> b/tools/testing/selftests/resctrl/resctrlfs.c
>>> index 52452bb0178a..bd81a13ff9df 100644
>>> --- a/tools/testing/selftests/resctrl/resctrlfs.c
>>> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
>>> @@ -365,11 +365,7 @@ void run_benchmark(int signum, siginfo_t *info, void
>>> *ucontext)
>>> memflush = atoi(benchmark_cmd[3]);
>>> operation = atoi(benchmark_cmd[4]);
>>> sprintf(resctrl_val, "%s", benchmark_cmd[5]);
>>> -
>>> - if (strcmp(resctrl_val, "cqm") != 0)
>>> - buffer_span = span * MB;
>>> - else
>>> - buffer_span = span;
>>> + buffer_span = span * MB;
>>
>> This change seems to change the buffer_span used by the other tests. It
>> is not obvious why this change is made to other tests while this commit
>> intends to focus on the cache monitoring test. Perhaps this can be split
>> into a separate patch to make this clear?
>
Got it. Thank you.
Reinette
