* Questions about complete @ 2011-01-06 6:18 loody 2011-01-06 6:33 ` Pavan Savoy 0 siblings, 1 reply; 11+ messages in thread From: loody @ 2011-01-06 6:18 UTC (permalink / raw) To: kernelnewbies Dear all: I know complete will wake up the process who call wait_complete. Is there any methods I can use to measure how long from calling complete to the process that detect done=1? Regards, miloody ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 6:18 Questions about complete loody @ 2011-01-06 6:33 ` Pavan Savoy 2011-01-06 6:53 ` loody 0 siblings, 1 reply; 11+ messages in thread From: Pavan Savoy @ 2011-01-06 6:33 UTC (permalink / raw) To: kernelnewbies On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: > > Dear all: > I know complete will wake up the process who call wait_complete. > Is there any methods I can use to measure how long from calling > complete to the process that detect done=1? > Regards, > miloody returned value of wait_for_completion_timeout ? _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies at kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 6:33 ` Pavan Savoy @ 2011-01-06 6:53 ` loody 2011-01-06 6:56 ` Pavan Savoy 0 siblings, 1 reply; 11+ messages in thread From: loody @ 2011-01-06 6:53 UTC (permalink / raw) To: kernelnewbies hi: 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >> >> Dear all: >> I know complete will wake up the process who call wait_complete. >> Is there any methods I can use to measure how long from calling >> complete to the process that detect done=1? >> Regards, >> miloody > > returned value of wait_for_completion_timeout ? No. I want to measure the duration of complete to the time of wake up process who is pending on wait. thank you. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 6:53 ` loody @ 2011-01-06 6:56 ` Pavan Savoy 2011-01-06 8:05 ` loody 0 siblings, 1 reply; 11+ messages in thread From: Pavan Savoy @ 2011-01-06 6:56 UTC (permalink / raw) To: kernelnewbies On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: > hi: > > 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >>> >>> Dear all: >>> I know complete will wake up the process who call wait_complete. >>> Is there any methods I can use to measure how long from calling >>> complete to the process that detect done=1? >>> Regards, >>> miloody >> >> returned value of wait_for_completion_timeout ? > No. > I want to measure the duration of complete to the time of wake up > process who is pending on wait. Ah, Ok, Got it... I would do a copy of jiffies before the complete and do a diff for jiffies after the wait_for_ ... I suppose there would be much more better/optimized way .... > thank you. > ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 6:56 ` Pavan Savoy @ 2011-01-06 8:05 ` loody 2011-01-06 8:51 ` Rajat Sharma 0 siblings, 1 reply; 11+ messages in thread From: loody @ 2011-01-06 8:05 UTC (permalink / raw) To: kernelnewbies hi: 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: >> hi: >> >> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >>>> >>>> Dear all: >>>> I know complete will wake up the process who call wait_complete. >>>> Is there any methods I can use to measure how long from calling >>>> complete to the process that detect done=1? >>>> Regards, >>>> miloody >>> >>> returned value of wait_for_completion_timeout ? >> No. >> I want to measure the duration of complete to the time of wake up >> process who is pending on wait. > > Ah, Ok, Got it... > I would do a copy of jiffies before the complete and do a diff for > jiffies after the > wait_for_ ... > > I suppose there would be much more better/optimized way .... thank U :) why I ask so is I am porting kernel to other platform right now. and I found the time of getting complete is too long. What I mean is function A call wait_complete_timeout function B complete theoretically A will get complete and leave successfully but my platform A will told me that before timeout the complete is not got. Regards, miloody ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 8:05 ` loody @ 2011-01-06 8:51 ` Rajat Sharma 2011-01-07 14:21 ` loody 0 siblings, 1 reply; 11+ messages in thread From: Rajat Sharma @ 2011-01-06 8:51 UTC (permalink / raw) To: kernelnewbies Hi loody, calling complete will make the waiter process runnable but won't necessarily switch to waiter thread and make it run. Its upto scheduler to pick this process from run queue and execute based on its priority value. I think there is not deterministic time in which the waiter process will start executing. Probably what you want to do is calibrate timeout value in wait_for_completion_timeout. I would suggest to do a binary search between minimum timeout value (latency by which function A calls complete, though this process can also schedule in between) to max value (max your application can afford). Rajat On Thu, Jan 6, 2011 at 1:35 PM, loody <miloody@gmail.com> wrote: > hi: > > 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >> On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: >>> hi: >>> >>> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >>>>> >>>>> Dear all: >>>>> I know complete will wake up the process who call wait_complete. >>>>> Is there any methods I can use to measure how long from calling >>>>> complete to the process that detect done=1? >>>>> Regards, >>>>> miloody >>>> >>>> returned value of wait_for_completion_timeout ? >>> No. >>> I want to measure the duration of complete to the time of wake up >>> process who is pending on wait. >> >> Ah, Ok, Got it... >> I would do a copy of jiffies before the complete and do a diff for >> jiffies after the >> wait_for_ ... >> >> I suppose there would be much more better/optimized way .... > thank U :) > why I ask so is I am porting kernel to other platform right now. > and I found the time of getting complete is too long. > What I mean is > function A call wait_complete_timeout > function B complete > theoretically A will get complete and leave successfully > but my platform A will told me that before timeout the complete is not got. > > Regards, > miloody > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies at kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-06 8:51 ` Rajat Sharma @ 2011-01-07 14:21 ` loody 0 siblings, 0 replies; 11+ messages in thread From: loody @ 2011-01-07 14:21 UTC (permalink / raw) To: kernelnewbies hi all: 2011/1/6 Rajat Sharma <fs.rajat@gmail.com>: > Hi loody, > > calling complete will make the waiter process runnable but won't > necessarily switch to waiter thread and make it run. Its upto > scheduler to pick this process from run queue and execute based on its > priority value. I think there is not deterministic time in which the > waiter process will start executing. > > Probably what you want to do is calibrate timeout value in > wait_for_completion_timeout. I would suggest to do a binary search > between minimum timeout value (latency by which function A calls > complete, though this process can also schedule in between) to max > value (max your application can afford). > > Rajat > > On Thu, Jan 6, 2011 at 1:35 PM, loody <miloody@gmail.com> wrote: >> hi: >> >> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>> On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: >>>> hi: >>>> >>>> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>>>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >>>>>> >>>>>> Dear all: >>>>>> I know complete will wake up the process who call wait_complete. >>>>>> Is there any methods I can use to measure how long from calling >>>>>> complete to the process that detect done=1? >>>>>> Regards, >>>>>> miloody >>>>> >>>>> returned value of wait_for_completion_timeout ? >>>> No. >>>> I want to measure the duration of complete to the time of wake up >>>> process who is pending on wait. >>> >>> Ah, Ok, Got it... >>> I would do a copy of jiffies before the complete and do a diff for >>> jiffies after the >>> wait_for_ ... >>> >>> I suppose there would be much more better/optimized way .... >> thank U :) >> why I ask so is I am porting kernel to other platform right now. >> and I found the time of getting complete is too long. >> What I mean is >> function A call wait_complete_timeout >> function B complete >> theoretically A will get complete and leave successfully >> but my platform A will told me that before timeout the complete is not got. I doubt my problem comes from cpu timer interrupt is so often such that when function B get the change to complete, the left time is almost exhausted. for not to be confused, I take following jiffies for example: 1 2 3 4 5 6 8 start wait B try complete time out B try to complete but cpu timer keep firing and at 8 it is time out. My platform is mips and is there any possibility to only let cpu timer be preemptible? BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? -- Regards, miloody ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Questions about complete @ 2011-01-07 14:21 ` loody 0 siblings, 0 replies; 11+ messages in thread From: loody @ 2011-01-07 14:21 UTC (permalink / raw) To: Linux MIPS Mailing List; +Cc: kernelnewbies hi all: 2011/1/6 Rajat Sharma <fs.rajat@gmail.com>: > Hi loody, > > calling complete will make the waiter process runnable but won't > necessarily switch to waiter thread and make it run. Its upto > scheduler to pick this process from run queue and execute based on its > priority value. I think there is not deterministic time in which the > waiter process will start executing. > > Probably what you want to do is calibrate timeout value in > wait_for_completion_timeout. I would suggest to do a binary search > between minimum timeout value (latency by which function A calls > complete, though this process can also schedule in between) to max > value (max your application can afford). > > Rajat > > On Thu, Jan 6, 2011 at 1:35 PM, loody <miloody@gmail.com> wrote: >> hi: >> >> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>> On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: >>>> hi: >>>> >>>> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: >>>>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: >>>>>> >>>>>> Dear all: >>>>>> I know complete will wake up the process who call wait_complete. >>>>>> Is there any methods I can use to measure how long from calling >>>>>> complete to the process that detect done=1? >>>>>> Regards, >>>>>> miloody >>>>> >>>>> returned value of wait_for_completion_timeout ? >>>> No. >>>> I want to measure the duration of complete to the time of wake up >>>> process who is pending on wait. >>> >>> Ah, Ok, Got it... >>> I would do a copy of jiffies before the complete and do a diff for >>> jiffies after the >>> wait_for_ ... >>> >>> I suppose there would be much more better/optimized way .... >> thank U :) >> why I ask so is I am porting kernel to other platform right now. >> and I found the time of getting complete is too long. >> What I mean is >> function A call wait_complete_timeout >> function B complete >> theoretically A will get complete and leave successfully >> but my platform A will told me that before timeout the complete is not got. I doubt my problem comes from cpu timer interrupt is so often such that when function B get the change to complete, the left time is almost exhausted. for not to be confused, I take following jiffies for example: 1 2 3 4 5 6 8 start wait B try complete time out B try to complete but cpu timer keep firing and at 8 it is time out. My platform is mips and is there any possibility to only let cpu timer be preemptible? BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? -- Regards, miloody ^ permalink raw reply [flat|nested] 11+ messages in thread
* Questions about complete 2011-01-07 14:21 ` loody (?) @ 2011-01-08 10:24 ` Rajat Sharma -1 siblings, 0 replies; 11+ messages in thread From: Rajat Sharma @ 2011-01-08 10:24 UTC (permalink / raw) To: kernelnewbies > B try to complete but cpu timer keep firing and at 8 it is time out. > My platform is mips and is there any possibility to only let cpu timer > be preemptible? > This seems really strange because when B calls complete, it sets up condition variable value i.e. completion->done++ by disabling the local interrupts. Following is code snippet from complete function: spin_lock_irqsave(&x->wait.lock, flags); // This will disable interrupts x->done++; // signals completion __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); So now even if process A does not get a chance to execute and completion timeout occurs before that, as you have shown in your example, process A would still correctly knows about completion because x->done was already set. Pleas look at the code snippet for do_wait_for_common called from wait_for_completion_timeout: if (!x->done) { .... do { .... } while (!x->done && timeout); __remove_wait_queue(&x->wait, &wait); if (!x->done) return timeout; } x->done--; return timeout ?: 1; >From above code, even if timeout expires i.e. timeout=0 and x->done is already set, this function will still return 1. > BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? completion functions taking spin_lock_irqsave, so timer ISR should not preempt the complete API. Rajat On Fri, Jan 7, 2011 at 7:51 PM, loody <miloody@gmail.com> wrote: > > hi all: > > 2011/1/6 Rajat Sharma <fs.rajat@gmail.com>: > > Hi loody, > > > > calling complete will make the waiter process runnable but won't > > necessarily switch to waiter thread and make it run. Its upto > > scheduler to pick this process from run queue and execute based on its > > priority value. I think there is not deterministic time in which the > > waiter process will start executing. > > > > Probably what you want to do is calibrate timeout value in > > wait_for_completion_timeout. I would suggest to do a binary search > > between minimum timeout value (latency by which function A calls > > complete, though this process can also schedule in between) to max > > value (max your application can afford). > > > > Rajat > > > > On Thu, Jan 6, 2011 at 1:35 PM, loody <miloody@gmail.com> wrote: > >> hi: > >> > >> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > >>> On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: > >>>> hi: > >>>> > >>>> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > >>>>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: > >>>>>> > >>>>>> Dear all: > >>>>>> I know complete will wake up the process who call wait_complete. > >>>>>> Is there any methods I can use to measure how long from calling > >>>>>> complete to the process that detect done=1? > >>>>>> Regards, > >>>>>> miloody > >>>>> > >>>>> returned value of wait_for_completion_timeout ? > >>>> No. > >>>> I want to measure the duration of complete to the time of wake up > >>>> process who is pending on wait. > >>> > >>> Ah, Ok, Got it... > >>> I would do a copy of jiffies before the complete and do a diff for > >>> jiffies after the > >>> wait_for_ ... > >>> > >>> I suppose there would be much more better/optimized way .... > >> thank U :) > >> why I ask so is I am porting kernel to other platform right now. > >> and I found the time of getting complete is too long. > >> What I mean is > >> function A call wait_complete_timeout > >> function B complete > >> theoretically A will get complete and leave successfully > >> but my platform A will told me that before timeout the complete is not got. > > I doubt my problem comes from cpu timer interrupt is so often such > that when function B get the change to complete, the left time is > almost exhausted. > for not to be confused, I take following jiffies for example: > 1 ? ? ? ? ? ? ? 2 ? ? ? ? ? ?3 ? ? ? ? ? ?4 ? ? ? ? ? ?5 > 6 ? ? ? ? ? ?8 > start wait ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?B try complete > ? ? ? time out > > B try to complete but cpu timer keep firing and at 8 it is time out. > My platform is mips and is there any possibility to only let cpu timer > be preemptible? > > BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? > > > -- > Regards, > miloody > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies at kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Questions about complete @ 2011-01-08 10:24 ` Rajat Sharma 0 siblings, 0 replies; 11+ messages in thread From: Rajat Sharma @ 2011-01-08 10:24 UTC (permalink / raw) To: loody; +Cc: Linux MIPS Mailing List, kernelnewbies > B try to complete but cpu timer keep firing and at 8 it is time out. > My platform is mips and is there any possibility to only let cpu timer > be preemptible? > This seems really strange because when B calls complete, it sets up condition variable value i.e. completion->done++ by disabling the local interrupts. Following is code snippet from complete function: spin_lock_irqsave(&x->wait.lock, flags); // This will disable interrupts x->done++; // signals completion __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); So now even if process A does not get a chance to execute and completion timeout occurs before that, as you have shown in your example, process A would still correctly knows about completion because x->done was already set. Pleas look at the code snippet for do_wait_for_common called from wait_for_completion_timeout: if (!x->done) { .... do { .... } while (!x->done && timeout); __remove_wait_queue(&x->wait, &wait); if (!x->done) return timeout; } x->done--; return timeout ?: 1; ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Questions about complete @ 2011-01-08 10:24 ` Rajat Sharma 0 siblings, 0 replies; 11+ messages in thread From: Rajat Sharma @ 2011-01-08 10:24 UTC (permalink / raw) To: loody; +Cc: Linux MIPS Mailing List, kernelnewbies > B try to complete but cpu timer keep firing and at 8 it is time out. > My platform is mips and is there any possibility to only let cpu timer > be preemptible? > This seems really strange because when B calls complete, it sets up condition variable value i.e. completion->done++ by disabling the local interrupts. Following is code snippet from complete function: spin_lock_irqsave(&x->wait.lock, flags); // This will disable interrupts x->done++; // signals completion __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); So now even if process A does not get a chance to execute and completion timeout occurs before that, as you have shown in your example, process A would still correctly knows about completion because x->done was already set. Pleas look at the code snippet for do_wait_for_common called from wait_for_completion_timeout: if (!x->done) { .... do { .... } while (!x->done && timeout); __remove_wait_queue(&x->wait, &wait); if (!x->done) return timeout; } x->done--; return timeout ?: 1; From above code, even if timeout expires i.e. timeout=0 and x->done is already set, this function will still return 1. > BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? completion functions taking spin_lock_irqsave, so timer ISR should not preempt the complete API. Rajat On Fri, Jan 7, 2011 at 7:51 PM, loody <miloody@gmail.com> wrote: > > hi all: > > 2011/1/6 Rajat Sharma <fs.rajat@gmail.com>: > > Hi loody, > > > > calling complete will make the waiter process runnable but won't > > necessarily switch to waiter thread and make it run. Its upto > > scheduler to pick this process from run queue and execute based on its > > priority value. I think there is not deterministic time in which the > > waiter process will start executing. > > > > Probably what you want to do is calibrate timeout value in > > wait_for_completion_timeout. I would suggest to do a binary search > > between minimum timeout value (latency by which function A calls > > complete, though this process can also schedule in between) to max > > value (max your application can afford). > > > > Rajat > > > > On Thu, Jan 6, 2011 at 1:35 PM, loody <miloody@gmail.com> wrote: > >> hi: > >> > >> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > >>> On Thu, Jan 6, 2011 at 12:23 PM, loody <miloody@gmail.com> wrote: > >>>> hi: > >>>> > >>>> 2011/1/6 Pavan Savoy <pavan_savoy@sify.com>: > >>>>> On Thu, Jan 6, 2011 at 11:48 AM, loody <miloody@gmail.com> wrote: > >>>>>> > >>>>>> Dear all: > >>>>>> I know complete will wake up the process who call wait_complete. > >>>>>> Is there any methods I can use to measure how long from calling > >>>>>> complete to the process that detect done=1? > >>>>>> Regards, > >>>>>> miloody > >>>>> > >>>>> returned value of wait_for_completion_timeout ? > >>>> No. > >>>> I want to measure the duration of complete to the time of wake up > >>>> process who is pending on wait. > >>> > >>> Ah, Ok, Got it... > >>> I would do a copy of jiffies before the complete and do a diff for > >>> jiffies after the > >>> wait_for_ ... > >>> > >>> I suppose there would be much more better/optimized way .... > >> thank U :) > >> why I ask so is I am porting kernel to other platform right now. > >> and I found the time of getting complete is too long. > >> What I mean is > >> function A call wait_complete_timeout > >> function B complete > >> theoretically A will get complete and leave successfully > >> but my platform A will told me that before timeout the complete is not got. > > I doubt my problem comes from cpu timer interrupt is so often such > that when function B get the change to complete, the left time is > almost exhausted. > for not to be confused, I take following jiffies for example: > 1 2 3 4 5 > 6 8 > start wait B try complete > time out > > B try to complete but cpu timer keep firing and at 8 it is time out. > My platform is mips and is there any possibility to only let cpu timer > be preemptible? > > BTW, in x86 or other ARCH, will they try to let timer ISR be preemptible? > > > -- > Regards, > miloody > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2011-01-08 10:24 UTC | newest] Thread overview: 11+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-01-06 6:18 Questions about complete loody 2011-01-06 6:33 ` Pavan Savoy 2011-01-06 6:53 ` loody 2011-01-06 6:56 ` Pavan Savoy 2011-01-06 8:05 ` loody 2011-01-06 8:51 ` Rajat Sharma 2011-01-07 14:21 ` loody 2011-01-07 14:21 ` loody 2011-01-08 10:24 ` Rajat Sharma 2011-01-08 10:24 ` Rajat Sharma 2011-01-08 10:24 ` Rajat Sharma
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