Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH] rudimentary tracing for Classic RCU | Date | Thu, 9 Oct 2008 16:14:26 +0900 (JST) |
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Hi Lai-san,
> >> In this case, why not define it as: > >> static char buf[20*NR_CPUS + 100]; > > > > Actually you should near never use NR_CPUS now but always num_possible_cpus() > > (or even num_online_cpus()) Using NR_CPUS can lead to extreme waste > > of memory on kernels which are compiled for 4096 CPUs for example. > > > > And with num_possible_cpus() kmalloc is needed. > > I thought the default value of NR_CPUS is 32.
it's pointless. Almost distribution use _very_ large NR_CPUS (likes 4096). So, We should concern large NR_CPUS.
> > if NR_CPUS is too large, I think using seq_file is good idea, > and rcuclassic_trace_mutex is not need too.
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