On 2 April 2015 at 19:15, Peter Zijlstra peterz@infradead.org wrote:
On Thu, Apr 02, 2015 at 04:21:22PM +0530, Viresh Kumar wrote:
+#define for_each_active_base(_index, _base, _cpu_base, _active_bases) \
for ((_active_bases) = (_cpu_base)->active_bases; \(_index) = ffs(_active_bases), \(_base) = (_cpu_base)->clock_base + (_index) - 1, (_index); \(_active_bases) &= ~(1 << ((_index) - 1)))Can't use ffs here, some people end up using asm-generic/bitops/ffs.h and that sucks.
Esp for small vectors like here, the unconditional iteration is faster.
Okay what about this instead (This is the best I could write :).) ?
+static inline int __next_bit(unsigned int active_bases, int bit) +{ + do { + if (active_bases & (1 << bit)) + return bit; + } while (++bit < HRTIMER_MAX_CLOCK_BASES); + + /* We should never reach here */ + return 0; +} +/* + * for_each_active_base: iterate over all active clock bases + * @_bit: 'int' variable for internal purpose + * @_base: holds pointer to a active clock base + * @_cpu_base: cpu base to iterate on + * @_active_bases: 'unsigned int' variable for internal purpose + */ +#define for_each_active_base(_bit, _base, _cpu_base, _active_bases) \ + for ((_active_bases) = (_cpu_base)->active_bases, (_bit) = -1; \ + (_active_bases) && \ + ((_bit) = __next_bit(_active_bases, ++_bit), \ + (_base) = (_cpu_base)->clock_base + _bit); \ + (_active_bases) &= ~(1 << (_bit))) +
Tested it well with the help of: http://pastebin.com/cYyB513D, with inputs from 0 to 15.
I will send it formally if it looks fine to you ..