On Fri, 28 Nov 2014 19:23:37 +0100 Frederic Weisbecker <[email protected]> wrote:
> Kernel cpu stats are stored in cputime_t which is an architecture > defined type, and hence a bit opaque and requiring accessors and mutators > for any operation. > > Converting them to nsecs simplifies the code a little bit. Quite honestly I do not see much of an improvement here, on set of functions (cputime_to_xxx) gets replaced by another (nsecs_to_xxx). On the contrary for s390 I see a degradation, consider a hunk like this: > @@ -128,9 +128,9 @@ static inline u64 get_cpu_idle_time_jiffy(unsigned int > cpu, u64 *wall) > > idle_time = cur_wall_time - busy_time; > if (wall) > - *wall = cputime_to_usecs(cur_wall_time); > + *wall = div_u64(cur_wall_time, NSEC_PER_USEC); > > - return cputime_to_usecs(idle_time); > + return div_u64(idle_time, NSEC_PER_USEC); > } > > u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy) For s390 cputime_to_usecs is a shift, with the new code we now have a division. Fortunately this is in a piece of code that s390 does not use.. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- 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/
