On Fri, Apr 08, 2016 at 07:44:14PM +0200, Peter Zijlstra wrote: > On Fri, Apr 08, 2016 at 02:55:22PM +0200, Frederic Weisbecker wrote: > > > > @@ -4540,17 +4568,8 @@ static void cpu_load_update(struct rq *this_rq, > > > > unsigned long this_load, > > > > > > > > /* scale is effectively 1 << i now, and >> i divides by > > > > scale */ > > > > > > > > - old_load = this_rq->cpu_load[i]; > > > #ifdef CONFIG_NO_HZ_COMMON > > > > - old_load = decay_load_missed(old_load, pending_updates > > > > - 1, i); > > > > - if (tickless_load) { > > > > - old_load -= decay_load_missed(tickless_load, > > > > pending_updates - 1, i); > > > > - /* > > > > - * old_load can never be a negative value > > > > because a > > > > - * decayed tickless_load cannot be greater than > > > > the > > > > - * original tickless_load. > > > > - */ > > > > - old_load += tickless_load; > > > > - } > > > #endif > > > > Ah sure, if you prefer it that way, I can do that. > > Yes please. I normally favour the thing you did, but here it makes > tricky code that much harder to read.
So I tried and it warns about the unused variable tickless_load, so I would need two scattered ifdeffery in the function: @@ -4528,7 +4529,9 @@ decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) static void cpu_load_update(struct rq *this_rq, unsigned long this_load, unsigned long pending_updates) { +#ifdef CONFIG_NO_HZ_COMMON unsigned long tickless_load = this_rq->cpu_load[0]; +#endif int i, scale; this_rq->nr_load_updates++; @@ -4541,6 +4544,7 @@ static void cpu_load_update(struct rq *this_rq, unsigned long this_load, /* scale is effectively 1 << i now, and >> i divides by scale */ old_load = this_rq->cpu_load[i]; +#ifdef CONFIG_NO_HZ_COMMON old_load = decay_load_missed(old_load, pending_updates - 1, i); if (tickless_load) { old_load -= decay_load_missed(tickless_load, pending_updates - 1, i); @@ -4551,6 +4555,7 @@ static void cpu_load_update(struct rq *this_rq, unsigned long this_load, */ old_load += tickless_load; } +#endif new_load = this_load; /* * Round up the averaging division if load is increasing. This Are you still sure you don't want the ifdeffed inline function? Thanks.