Messages in this thread | | | Date | Mon, 19 Nov 2018 09:09:16 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] debugobjects: add a new Kconfig for POOL_SIZE |
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Qian,
On Sun, 18 Nov 2018, Qian Cai wrote: > > On Nov 18, 2018, at 1:21 PM, Thomas Gleixner <tglx@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.
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.
Thanks,
tglx
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