On 11/19/2018 08:27 AM, Qian Cai wrote: > On 11/19/18 at 3:09 AM, Thomas Gleixner wrote: > >> Qian, >> >> On Sun, 18 Nov 2018, Qian Cai wrote: >>>> On Nov 18, 2018, at 1:21 PM, Thomas Gleixner <t...@linutronix.de> wrote: >>>> On Sun, 18 Nov 2018, Qian Cai wrote: >>>>> As the results, systems have 60+ CPUs with both timer and workqueue >>>>> objects enabled could trigger "ODEBUG: Out of memory. ODEBUG disabled". >>>>> >>>>> Hence, add a new Kconfig option so users could adjust ODEBUG_POOL_SIZE >>>>> accordingly if either timer or workqueue objects are selected. >>>> why do we need a config option, when the required number can be deduced >>>> already from the active CONFIG_DEBUG_OBJECTS_* and NR_CPUS? >>>> >>> It because I am worry about the coupling between the implementation details >>> of >>> timers and workqueue objects, and the computation in the code you mentioned >>> here. For example, people could change workqueue.c to have different number >>> of worekqueues initialized during the early boot in the future which is >>> going to >>> affect the required pool size, and I am not sure if people are going to >>> adjust the >>> code in debugobjects.c here as well when they made changes like that. >>> >>> Also, the computation could become so complex depends on lots of config >>> options like perf, hrtimer, and combinations that I have not tested so far >>> which is >>> difficult to exhausted all the possibilities. >>> >>> Hence, I feel like the Kconfig option is more flexible and less error-prone. >> Quite the contrary. Config options are a pain and truly error-prone if you >> want to compile general purpose kernels as distributions do. >> > Ah, I never thought distributions people would > enable those debugging options.
Distros like RHEL usually ship two kernels - one for production and one for debug. The debug kernel does have debugobjects enabled. Cheers, Longman
