[PATCH 2/2] cyclic: parse cyclic list only if next cyclic timestamp is reached

[Patrice CHOTARD]

On 7/3/26 00:10, Marek Vasut wrote:
> On 7/2/26 5:24 PM, Patrice Chotard wrote:
>> On STM32MP157C-DK2, when using the "ums" command, in sleep_thread(),
>> ctrlc() is called every ~640ms which doesn't allows high reactivity when
>> user press CTRL+C in U-Boot console.
>>
>> In sleep_thread() loop, ctrlc() is called every 200000 iterations.
>> But schedule is called on each loop iteration.
>>
>> Optimize cyclic_run() in order to parse the cyclic list only is the
>> next cyclic to run is due.
>> During cyclic list parsing, save the nearest cyclic timestamp, which
>> allows to exit from next cyclic_run() call if no cyclic will be executed.
>>
>> This allow to save computation time :
>>    _ before : ctrlc() is called every ~640ms
>>    _ after  : ctrlc() is called every ~230ms
>>
>> Signed-off-by: Patrice Chotard <patrice.chotard at foss.st.com>
>> Cc: Marek Vasut <marek.vasut at mailbox.org>
>> ---
>>   common/cyclic.c                   | 12 ++++++++++++
>>   include/asm-generic/global_data.h |  4 ++++
>>   2 files changed, 16 insertions(+)
>>
>> diff --git a/common/cyclic.c b/common/cyclic.c
>> index b37cd6d8ff0..714d6863d5b 100644
>> --- a/common/cyclic.c
>> +++ b/common/cyclic.c
>> @@ -68,11 +68,17 @@ static void cyclic_run(void)
>>       struct cyclic_info *cyclic;
>>       struct hlist_node *tmp;
>>       u64 now, cpu_time;
>> +    u64 next_call = UINT64_MAX;
>>         /* Prevent recursion */
>>       if (gd->flags & GD_FLG_CYCLIC_RUNNING)
>>           return;
>>   +    /* check if the next cyclic function's timestamp is reached */
>> +    now = get_timer_us(0);
>> +    if (time_after_eq64(gd->next_cyclic_call, now))
>> +        return;
>> +
>>       gd->flags |= GD_FLG_CYCLIC_RUNNING;
>>       hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
>>           /*
>> @@ -102,7 +108,13 @@ static void cyclic_run(void)
>>                   cyclic->already_warned = true;
>>               }
>>           }
>> +        if (next_call > cyclic->next_call)
>> +            next_call = cyclic->next_call;
> 
> Can you move this entry to the beginning of the cyclic list, so that the entry with the earliest deadline would be right at the beginning of the list ? That should squeeze some more improvement out of this I think.

Hi Marek

I did a test, it doesn't bring any noticeable improvements, but nevertheless i will submit a v3 with this update.

> 
>>       }
>> +
>> +    if (next_call != UINT64_MAX)
> 
> Can the next_call literally hit UINT64_MAX in that one unlikely case ?
> You likely do need a separate flag, bool next_call_valid, to avoid that edge case.

In case, no cyclic has been registered, we don't parse the cyclic list and next_call stays set to UINT64_MAX
We don't want that next_cyclic_call be set to UINT64_MAX, otherwise in that case, we will always exit cyclic_run() before parsing cyclic list.

Patrice

> 
>> +        gd->next_cyclic_call = next_call;
>> +
>>       gd->flags &= ~GD_FLG_CYCLIC_RUNNING;
>>   }
> Thank you !