Hardware integer division is slow. The function damon_max_nr_accesses(), which is called very frequently (e.g., once per region per sample interval inside damon_update_region_access_rate), performs an integer division: attrs->aggr_interval / attrs->sample_interval. However, the struct damon_attrs already caches this exact ratio in the internal field aggr_samples (since earlier commits). We can eliminate the hardware division in the hot path by simply returning aggr_samples. This significantly reduces the CPU cycle overhead of updating the access rates for thousands of regions. Signed-off-by: Josh Law --- include/linux/damon.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/include/linux/damon.h b/include/linux/damon.h index 6bd71546f7b2..fffdb08326a2 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -960,8 +960,7 @@ static inline bool damon_target_has_pid(const struct damon_ctx *ctx) static inline unsigned int damon_max_nr_accesses(const struct damon_attrs *attrs) { /* {aggr,sample}_interval are unsigned long, hence could overflow */ - return min(attrs->aggr_interval / attrs->sample_interval, - (unsigned long)UINT_MAX); + return min(attrs->aggr_samples, (unsigned long)UINT_MAX); } -- 2.34.1