On Sun, Apr 27, 2014 at 11:29:21PM +0900, Namhyung Kim wrote: > Hi Jiri, > > 2014-04-17 (목), 19:39 +0200, Jiri Olsa: > > Caching registers value into an array. Got about 4% speed up > > of perf_reg_value function for report command processing > > dwarf unwind stacks. > > I'm not familiar with the code base, so probably silly questions: Where > does the speed up come from? IOW I don't know what's the difference > between the regs->regs and regs->cached_regs. And does the cached_regs > contain correct values of registers for each frame?
the current way register's value is accessed is to get its index in the sample's regs array.. based on register's id and the registers mask so each time you want register value you traverse the registers mask and count reg's index for the sample regs array this patch does this only once for each register (at the time it's first accessed) and cache its value in the array (cache_regs). The cache_mask is used to identify which regs are already cached. jirka -- 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/