Re: [PATCH v12 6/7] eal: add unit tests for atomic bit access functions

["Mattias Rönnblom" <hofors@lysator.liu.se>]

On 2024-10-10 12:45, David Marchand wrote:
> On Fri, Sep 20, 2024 at 12:57 PM Mattias Rönnblom
> <mattias.ronnblom@ericsson.com> wrote:
>> +       static int                                                      \
>> +       run_parallel_test_and_modify ## size(void *arg)         \
>> +       {                                                               \
>> +               struct parallel_test_and_set_lcore ## size *lcore = arg; \
>> +               uint64_t deadline = rte_get_timer_cycles() +            \
>> +                       PARALLEL_TEST_RUNTIME * rte_get_timer_hz();     \
>> +               do {                                                    \
>> +                       bool old_value;                                 \
>> +                       bool new_value = rte_rand() & 1;                \
>> +                       bool use_assign = rte_rand() & 1;               \
>> +                                                                       \
>> +                       if (use_assign)                                 \
>> +                               old_value = rte_bit_atomic_test_and_assign( \
>> +                                       lcore->word, lcore->bit, new_value, \
>> +                                       rte_memory_order_relaxed);      \
>> +                       else                                            \
>> +                               old_value = new_value ?                 \
>> +                                       rte_bit_atomic_test_and_set(    \
>> +                                               lcore->word, lcore->bit, \
>> +                                               rte_memory_order_relaxed) : \
>> +                                       rte_bit_atomic_test_and_clear(  \
>> +                                               lcore->word, lcore->bit, \
>> +                                               rte_memory_order_relaxed); \
>> +                       if (old_value != new_value)                     \
>> +                               lcore->flips++;                         \
>> +               } while (rte_get_timer_cycles() < deadline);            \
>> +                                                                       \
>> +               return 0;                                               \
>> +       }                                                               \
>> +                                                                       \
>> +       static int                                                      \
>> +       test_bit_atomic_parallel_test_and_modify ## size(void)          \
>> +       {                                                               \
>> +               unsigned int worker_lcore_id;                           \
>> +               uint ## size ## _t word = 0;                            \
>> +               unsigned int bit = rte_rand_max(size);                  \
>> +               struct parallel_test_and_set_lcore ## size lmain = {    \
>> +                       .word = &word,                                  \
>> +                       .bit = bit                                      \
>> +               };                                                      \
>> +               struct parallel_test_and_set_lcore ## size lworker = {  \
>> +                       .word = &word,                                  \
>> +                       .bit = bit                                      \
>> +               };                                                      \
>> +                                                                       \
>> +               if (rte_lcore_count() < 2) {                            \
>> +                       printf("Need multiple cores to run parallel test.\n"); \
>> +                       return TEST_SKIPPED;                            \
>> +               }                                                       \
>> +                                                                       \
>> +               worker_lcore_id = rte_get_next_lcore(-1, 1, 0);         \
>> +                                                                       \
>> +               int rc = rte_eal_remote_launch(run_parallel_test_and_modify ## size, \
>> +                                              &lworker, worker_lcore_id); \
>> +               TEST_ASSERT(rc == 0, "Worker thread launch failed");    \
>> +                                                                       \
>> +               run_parallel_test_and_modify ## size(&lmain);           \
>> +                                                                       \
>> +               rte_eal_mp_wait_lcore();                                \
>> +                                                                       \
>> +               uint64_t total_flips = lmain.flips + lworker.flips;     \
>> +               bool expected_value = total_flips % 2;                  \
>> +                                                                       \
>> +               TEST_ASSERT(expected_value == rte_bit_test(&word, bit), \
>> +                           "After %"PRId64" flips, the bit value "     \
>> +                           "should be %d", total_flips, expected_value); \
>> +                                                                       \
>> +               uint64_t expected_word = 0;                             \
>> +               rte_bit_assign(&expected_word, bit, expected_value);    \
>> +                                                                       \
>> +               TEST_ASSERT(expected_word == word, "Untouched bits have " \
>> +                           "changed value");                           \
>> +                                                                       \
>> +               return TEST_SUCCESS;                                    \
>> +       }
>> +
>> +GEN_TEST_BIT_PARALLEL_TEST_AND_MODIFY(32)
>> +GEN_TEST_BIT_PARALLEL_TEST_AND_MODIFY(64)
> 
> It appears this test failed once in the CI for an unrelated series
> (uAPI kernel header import):
> https://lab.dpdk.org/results/dashboard/testruns/logs/1385993/
> 
>   + TestCase [ 0] : test_bit_access32 succeeded
>   + TestCase [ 1] : test_bit_access64 succeeded
>   + TestCase [ 2] : test_bit_access32 succeeded
>   + TestCase [ 3] : test_bit_access64 succeeded
>   + TestCase [ 4] : test_bit_v_access32 succeeded
>   + TestCase [ 5] : test_bit_v_access64 succeeded
>   + TestCase [ 6] : test_bit_atomic_access32 succeeded
>   + TestCase [ 7] : test_bit_atomic_access64 succeeded
>   + TestCase [ 8] : test_bit_atomic_v_access32 succeeded
>   + TestCase [ 9] : test_bit_atomic_v_access64 succeeded
>   + TestCase [10] : test_bit_atomic_parallel_assign32 succeeded
>   + TestCase [11] : test_bit_atomic_parallel_assign64 succeeded
>   + TestCase [12] : test_bit_atomic_parallel_test_and_modify32 failed
>   + TestCase [13] : test_bit_atomic_parallel_test_and_modify64 succeeded
>   + TestCase [14] : test_bit_atomic_parallel_flip32 succeeded
>   + TestCase [15] : test_bit_atomic_parallel_flip64 succeeded
>   + TestCase [16] : test_bit_relaxed_set succeeded
>   + TestCase [17] : test_bit_relaxed_clear succeeded
>   + TestCase [18] : test_bit_relaxed_test_set_clear succeeded
> 
> EAL: Test assert test_bit_atomic_parallel_test_and_modify32 line 236
> failed: After 1070523 flips, the bit value should be 1
> 
> Please have a look.
> 
> 

OK. Nothing obvious from what I can see in the code. Unrelated: why did 
you remove all empty lines in the "template" macros? Makes them much 
harder to read.

I've been unable to reproduce this on my Raptor Lake x86_64 with GCC 
12.3 (CI machine used GCC 12.2).

I'll try if I have better luck on some other systems.