Re: [PATCH 4/9] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD

Johannes Weiner
2018-09-13T01:49:23Z

On Wed, Sep 12, 2018 at 04:28:28PM -0700, Andrew Morton wrote:
> On Tue, 28 Aug 2018 13:22:53 -0400 Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> > There are several definitions of those functions/macros in places that
> > mess with fixed-point load averages. Provide an official version.
>
> missed blk-iolatency.c for some reason?

Ah, that callsite came in with this merge window. Thanks for the
fixup.

> --- a/block/blk-iolatency.c~sched-loadavg-consolidate-load_int-load_frac-calc_load-fix
> +++ a/block/blk-iolatency.c
> @@ -512,7 +512,7 @@ static void iolatency_check_latencies(st
> exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1,
> div64_u64(iolat->cur_win_nsec,
> BLKIOLATENCY_EXP_BUCKET_SIZE));
> - CALC_LOAD(iolat->lat_avg, iolatency_exp_factors[exp_idx], stat.mean);
> + calc_load(iolat->lat_avg, iolatency_exp_factors[exp_idx], stat.mean);

The macro used to modify the avg parameter in place, but with the
function we need an explicit assignment to update the variable:

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 335c22317757..8793f1344e11 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -512,7 +512,8 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now)
exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1,
div64_u64(iolat->cur_win_nsec,
BLKIOLATENCY_EXP_BUCKET_SIZE));
- calc_load(iolat->lat_avg, iolatency_exp_factors[exp_idx], stat.mean);
+ iolat->lat_avg = calc_load(iolat->lat_avg,
+ iolatency_exp_factors[exp_idx], stat.mean);

/* Everything is ok and we don't need to adjust the scale. */
if (stat.mean <= iolat->min_lat_nsec &&