On Thu, 23 Apr 2015 11:33:08 +0100 Mel Gorman <mgor...@suse.de> wrote:
> __early_pfn_to_nid() in the generic and arch-specific implementations > use static variables to cache recent lookups. Without the cache > boot times are much higher due to the excessive memblock lookups but > it assumes that memory initialisation is single-threaded. Parallel > initialisation of struct pages will break that assumption so this patch > makes __early_pfn_to_nid() SMP-safe by requiring the caller to cache > recent search information. early_pfn_to_nid() keeps the same interface > but is only safe to use early in boot due to the use of a global static > variable. meminit_pfn_in_nid() is an SMP-safe version that callers must > maintain their own state for. Seems a bit awkward. > +struct __meminitdata mminit_pfnnid_cache global_init_state; > + > +/* Only safe to use early in boot when initialisation is single-threaded */ > int __meminit early_pfn_to_nid(unsigned long pfn) > { > int nid; > > - nid = __early_pfn_to_nid(pfn); > + /* The system will behave unpredictably otherwise */ > + BUG_ON(system_state != SYSTEM_BOOTING); Because of this. Providing a cache per cpu: struct __meminitdata mminit_pfnnid_cache global_init_state[NR_CPUS]; would be simpler? Also, `global_init_state' is a poor name for a kernel-wide symbol. -- 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/