On 11/27, Masami Hiramatsu wrote: > > (2013/11/27 2:43), Oleg Nesterov wrote: > > > > This doesn't allow to read the data from other CPUs, but at least > > the changes are simple and this_cpu_ is better than the reading > > from the obviously wrong address. > > Yeah, usually per_cpu variable is used in current cpu context. > > >> For the dynamic allocated per-cpu things, it is also good to give > >> a straight operation, like +10(percpu(%rdi)). > > > > Probably yes, but this needs more changes and I am still not sure > > this is really useful. And if we do this, we probably also need > > to allow to read from other CPUs... > > No, it is enough to provide "percpu(FETCHARG)" which just returns > current cpu's percpu variable address.
I don't really agree. I am not saying this is terribly useful, but: > (Note that kprobes handler > runs in interrupt) but this doesn't matter at all, I think. The code can execute, say, __percpu_counter_sum-like code. And even if we dump the .data..percpu memory (@percpu_symbol) the user might want to know the "global" state of this per-cpu object. And note that sometimes DEFINE_PER_CPU doesn't really connect to smp_processor_id(). Just for example, bp_cpuinfo[]. It is never used as this-cpu-data. This means that @bp_cpuinfo+whatever is always pointless. But anyway I agree, this is not that important, lets ignore. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
