Hi Chengdong,
> I submitted a PR (#18437) to address the CLOCK_BOOTTIME and CLOCK_MONOTONIC > time source issue. Could you please take a look when you have a chance? That's okay, you fixed a change that was made by commit 1c643b5cc on 30dec25. > So my suggestion is not to use CLOCK_MONOTONIC for nxsem_clockwait. if you > do not want the behavior you mentioned. That's not a solution. If nxsem_clockwait is only working as expected for CLOCK_REALTIME and CLOCK_BOOTTIME, it should al least return an error for other values. In my opinion, the main problem is that CLOCK_MONOTONIC's behaviour has been changed. This means that all uses of CLOCK_MONOTONIC must be checked and possibly changed. In nuttx, in the nuttx apps and in the all applications of all nuttx users! Am I the only one who had problems with that? BR, Mathias chengdong wang schrieb am 25.02.2026 03:46 (GMT +01:00): > Hi Mathias, > > I submitted a PR (#18437) to address the CLOCK_BOOTTIME and CLOCK_MONOTONIC > time source issue. Could you please take a look when you have a chance? > > Regarding the error you mentioned, I think it should be expected behavior, > because CLOCK_MONOTONIC excludes the time the system is suspended while the > wdog for sem timeout using the time that includes the suspended period. > > So my suggestion is not to use CLOCK_MONOTONIC for nxsem_clockwait. if you > do not want the behavior you mentioned. > > Best regards, > Chengdong > > <[email protected]> 于2026年2月20日周五 16:37写道： > >> >> Hi ChengDong, >> >> >> were you able to check my error message? >> How can we solve the problem? >> >> BR, >> >> Mathias >> >> >> >> >> chengdong wang schrieb am 06.02.2026 02:28 (GMT +01:00): >> >> > OK, I will take a look at this as soon as possible >> > >> > BR, >> > ChengDong >> > >> > Alan C. Assis <[email protected]> 于2026年2月6日周五 00:50写道： >> > >> >> Hi Mathias, >> >> >> >> Thank you for finding and reporting this issue. I'm CC Chengdong here. >> >> >> >> Chengdong, could you please take a look at this issue? >> >> >> >> BR, >> >> >> >> Alan >> >> >> >> On Thu, Feb 5, 2026 at 12:32 PM <[email protected]> wrote: >> >> >> >> > >> >> > Hello, >> >> > >> >> > I have problems with the following commit, which is part of PR #17199 >> >> > >> >> > commit c7b6442974545b92476615ef048633609d828e5b >> >> > Author: wangchengdong <[email protected]> >> >> > Date: Mon Oct 13 20:57:43 2025 +0800 >> >> > sched/clock: Improve CLOCK_MONOTONIC nxclock_gettime() >> >> > >> >> > Improve nxclock_gettime(), to get the system time excluding >> >> > the time that the system is suspended, when the clockid is >> >> > CLOCK_MONOTONIC >> >> > >> >> > Signed-off-by: Chengdong Wang [email protected] >> >> > >> >> > >> >> > >> >> > This commit changes the behaviour of CLOCK_MONOTONIC. It is running >> >> slower >> >> > than CLOCK_BOOTTIME now. >> >> > >> >> > I called sem_clockwait() with CLOCK_MONOTONIC, but the "if" in line >> 143 >> >> in >> >> > nuttx/sched/semaphore/sem_clockwait.c handles on two cases. I used >> >> > CLOCK_MONOTONIC to calculate the value "abstime", but >> wd_start_abstime() >> >> > uses CLOCK_BOOTTIME now. When the system in running for some time this >> >> > leads to an immediate timeout, because two different clocks are >> compared. >> >> > >> >> > >> >> > int nxsem_clockwait(FAR sem_t *sem, clockid_t clockid, >> >> > FAR const struct timespec *abstime) >> >> > { >> >> > ... >> >> > if (clockid == CLOCK_REALTIME) >> >> > { >> >> > wd_start_realtime(&rtcb->waitdog, abstime, >> >> > nxsem_timeout, (uintptr_t)rtcb); >> >> > } >> >> > else >> >> > { >> >> > wd_start_abstime(&rtcb->waitdog, abstime, >> >> > nxsem_timeout, (uintptr_t)rtcb); >> >> > } >> >> > ... >> >> > >> >> > >> >> > >> >> > For my understanding the change of CLOCK_MONOTONIC is not correct. >> >> > According to the POSIX definition >> >> > https://pubs.opengroup.org/onlinepubs/9799919799/ it must be a >> >> > "system-wide monotonic clock", CLOCK_BOOTTIME is not defined here. >> >> > >> >> > >> >> > On the other hand, if such a low level change is made, all usages >> should >> >> > be reviewed. There a lot of places where CLOCK_MONOTONIC is used in >> the >> >> > nuttx source code. And there are places like in nxsem_clockwait() >> where >> >> the >> >> > change leads to an error even though CLOCK_MONOTONIC is not used in >> the >> >> > code. >> >> > >> >> > >> >> > What do you think? >> >> > >> >> > BR, >> >> > Mathias >> >> > >> >> >> > >> >
