From: Denis Cheng <[EMAIL PROTECTED]> the explicit memset call could be optimized out by data initialization, thus all the fill working can be done by the compiler implicitly.
and C standard guaranteed all the unspecified data field initialized to zero. Signed-off-by: Denis Cheng <[EMAIL PROTECTED]> --- After comments in the former threads: http://lkml.org/lkml/2007/6/18/119 http://lkml.org/lkml/2007/6/18/48 On 6/18/07, Jan Engelhardt <[EMAIL PROTECTED]> wrote: > The cost is the same. "= {0}" is transformed into a bunch of movs, > or a rep mov, (At least for x86), so is equivalent to memset (which > will get transformed to __builtin_memset anyway). So I wonder > what this really buys. > > And, you do not even need the zero. Just write > ...[MAX_NR_ZONES] = {}; > Jan I also think this style of zero initialization would be better. so the patch is little different: --- arch/x86_64/mm/init.c.orig 2007-06-07 10:08:04.000000000 +0800 +++ arch/x86_64/mm/init.c 2007-06-23 13:12:26.000000000 +0800 @@ -406,8 +406,8 @@ void __cpuinit zap_low_mappings(int cpu) #ifndef CONFIG_NUMA void __init paging_init(void) { - unsigned long max_zone_pfns[MAX_NR_ZONES]; - memset(max_zone_pfns, 0, sizeof(max_zone_pfns)); + unsigned long max_zone_pfns[MAX_NR_ZONES] = {}; + max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN; max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN; max_zone_pfns[ZONE_NORMAL] = end_pfn; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
