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. > Its not really a problem to have a larger initial static pool which gets > freed after init anyway. So we can size it generously depending on the > config options and be done with it. > That’s a good point. I’ll send out a patch shortly.
