* preempt_disable and sleep() @ 2010-05-13 18:32 ratheesh k 2010-05-13 18:43 ` Sven-Thorsten Dietrich 0 siblings, 1 reply; 6+ messages in thread From: ratheesh k @ 2010-05-13 18:32 UTC (permalink / raw) To: linux-kernel, linux-rt-users I am running RT linux . /* code snippet */ preempt_disable() ........... sleep(10); '............ preempt_enable() will this sleep() will cause reschedule ?. if an interrupt comes while premption is disabled , how it is handled ?. Thanks, Ratheesh ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: preempt_disable and sleep() 2010-05-13 18:32 preempt_disable and sleep() ratheesh k @ 2010-05-13 18:43 ` Sven-Thorsten Dietrich 2010-05-14 2:46 ` ratheesh k 0 siblings, 1 reply; 6+ messages in thread From: Sven-Thorsten Dietrich @ 2010-05-13 18:43 UTC (permalink / raw) To: ratheesh k; +Cc: linux-kernel, linux-rt-users On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote: > I am running RT linux . > > /* code snippet */ > > preempt_disable() > ........... > sleep(10); > '............ > preempt_enable() > > > will this sleep() will cause reschedule ?. > Why would you do this? If you had tried this code, you would have seen the corresponding stack dump on the console. > if an interrupt comes while premption is disabled , how it is handled ?. > Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[] and the type of interrupt. RT threaded IRQs would not run until preemption is enabled on a single core system. > Thanks, > Ratheesh > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: preempt_disable and sleep() 2010-05-13 18:43 ` Sven-Thorsten Dietrich @ 2010-05-14 2:46 ` ratheesh k 0 siblings, 0 replies; 6+ messages in thread From: ratheesh k @ 2010-05-14 2:46 UTC (permalink / raw) To: Sven-Thorsten Dietrich; +Cc: linux-kernel, linux-rt-users On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich <thebigcorporation@gmail.com> wrote: > Why would you do this? I was reading some linux kernel journel about preempt_disable() . This a doubt came to me . > If you had tried this code, you would have seen the corresponding stack > dump on the console. Why it so .? could you explain a little more ? .sleep() will schedule () , which inturn give back control to kernel . Thank, Ratheesh On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich <thebigcorporation@gmail.com> wrote: > On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote: >> I am running RT linux . >> >> /* code snippet */ >> >> preempt_disable() >> ........... >> sleep(10); >> '............ >> preempt_enable() >> >> >> will this sleep() will cause reschedule ?. >> > > Why would you do this? > > If you had tried this code, you would have seen the corresponding stack > dump on the console. > >> if an interrupt comes while premption is disabled , how it is handled ?. >> > > Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[] > and the type of interrupt. > > RT threaded IRQs would not run until preemption is enabled on a single > core system. > > > >> Thanks, >> Ratheesh >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: preempt_disable and sleep() @ 2010-05-14 2:46 ` ratheesh k 0 siblings, 0 replies; 6+ messages in thread From: ratheesh k @ 2010-05-14 2:46 UTC (permalink / raw) To: Sven-Thorsten Dietrich; +Cc: linux-kernel, linux-rt-users On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich <thebigcorporation@gmail.com> wrote: > Why would you do this? I was reading some linux kernel journel about preempt_disable() . This a doubt came to me . > If you had tried this code, you would have seen the corresponding stack > dump on the console. Why it so .? could you explain a little more ? .sleep() will schedule () , which inturn give back control to kernel . Thank, Ratheesh On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich <thebigcorporation@gmail.com> wrote: > On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote: >> I am running RT linux . >> >> /* code snippet */ >> >> preempt_disable() >> ........... >> sleep(10); >> '............ >> preempt_enable() >> >> >> will this sleep() will cause reschedule ?. >> > > Why would you do this? > > If you had tried this code, you would have seen the corresponding stack > dump on the console. > >> if an interrupt comes while premption is disabled , how it is handled ?. >> > > Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[] > and the type of interrupt. > > RT threaded IRQs would not run until preemption is enabled on a single > core system. > > > >> Thanks, >> Ratheesh >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: preempt_disable and sleep() 2010-05-14 2:46 ` ratheesh k @ 2010-05-14 3:37 ` Paul E. McKenney -1 siblings, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2010-05-14 3:37 UTC (permalink / raw) To: ratheesh k; +Cc: Sven-Thorsten Dietrich, linux-kernel, linux-rt-users On Fri, May 14, 2010 at 08:16:07AM +0530, ratheesh k wrote: > On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich > <thebigcorporation@gmail.com> wrote: > > > Why would you do this? > I was reading some linux kernel journel about preempt_disable() . This > a doubt came to me . > > > > If you had tried this code, you would have seen the corresponding stack > > dump on the console. > > > Why it so .? could you explain a little more ? .sleep() will schedule > () , which inturn give back control to kernel . Sleeping in the kernel with preemption disabled is considered to be a bug. So the scheduler will print an error and a stack dump when this happens. In contrast, it is OK to do the following: preempt_disable(); do_something(); preempt_enable(); schedule(); preempt_disable(); do_something_else(); preempt_enable(); Thanx, Paul > Thank, > Ratheesh > > On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich > <thebigcorporation@gmail.com> wrote: > > On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote: > >> I am running RT linux . > >> > >> /* code snippet */ > >> > >> preempt_disable() > >> ........... > >> sleep(10); > >> '............ > >> preempt_enable() > >> > >> > >> will this sleep() will cause reschedule ?. > >> > > > > Why would you do this? > > > > If you had tried this code, you would have seen the corresponding stack > > dump on the console. > > > >> if an interrupt comes while premption is disabled , how it is handled ?. > >> > > > > Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[] > > and the type of interrupt. > > > > RT threaded IRQs would not run until preemption is enabled on a single > > core system. > > > > > > > >> Thanks, > >> Ratheesh > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: preempt_disable and sleep() @ 2010-05-14 3:37 ` Paul E. McKenney 0 siblings, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2010-05-14 3:37 UTC (permalink / raw) To: ratheesh k; +Cc: Sven-Thorsten Dietrich, linux-kernel, linux-rt-users On Fri, May 14, 2010 at 08:16:07AM +0530, ratheesh k wrote: > On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich > <thebigcorporation@gmail.com> wrote: > > > Why would you do this? > I was reading some linux kernel journel about preempt_disable() . This > a doubt came to me . > > > > If you had tried this code, you would have seen the corresponding stack > > dump on the console. > > > Why it so .? could you explain a little more ? .sleep() will schedule > () , which inturn give back control to kernel . Sleeping in the kernel with preemption disabled is considered to be a bug. So the scheduler will print an error and a stack dump when this happens. In contrast, it is OK to do the following: preempt_disable(); do_something(); preempt_enable(); schedule(); preempt_disable(); do_something_else(); preempt_enable(); Thanx, Paul > Thank, > Ratheesh > > On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich > <thebigcorporation@gmail.com> wrote: > > On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote: > >> I am running RT linux . > >> > >> /* code snippet */ > >> > >> preempt_disable() > >> ........... > >> sleep(10); > >> '............ > >> preempt_enable() > >> > >> > >> will this sleep() will cause reschedule ?. > >> > > > > Why would you do this? > > > > If you had tried this code, you would have seen the corresponding stack > > dump on the console. > > > >> if an interrupt comes while premption is disabled , how it is handled ?. > >> > > > > Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[] > > and the type of interrupt. > > > > RT threaded IRQs would not run until preemption is enabled on a single > > core system. > > > > > > > >> Thanks, > >> Ratheesh > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-05-14 3:37 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2010-05-13 18:32 preempt_disable and sleep() ratheesh k 2010-05-13 18:43 ` Sven-Thorsten Dietrich 2010-05-14 2:46 ` ratheesh k 2010-05-14 2:46 ` ratheesh k 2010-05-14 3:37 ` Paul E. McKenney 2010-05-14 3:37 ` Paul E. McKenney
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