Hi Xin,
On Wed, 14 Sep 2022 19:38:59 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote:
> In damon_lru_sort_new_hot_scheme() and damon_lru_sort_new_cold_scheme(),
> they have so much in common, so we can combine them into a single
> function, and we just need to distinguish their differences.
Thank you again for patiently waiting for my changes and reworking on this!
>
> Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
> ---
> mm/damon/lru_sort.c | 57 ++++++++++++++++++++++-----------------------
> 1 file changed, 28 insertions(+), 29 deletions(-)
>
> diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
> index 07a0908963fd..2eac907e866d 100644
> --- a/mm/damon/lru_sort.c
> +++ b/mm/damon/lru_sort.c
> @@ -135,17 +135,40 @@ DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat,
> static struct damon_ctx *ctx;
> static struct damon_target *target;
>
> -static struct damos *damon_lru_sort_new_scheme(
> - struct damos_access_pattern *pattern, enum damos_action action)
> +static struct damos *damon_lru_sort_new_scheme(unsigned int thres,
> + enum damos_action action)
> {
> + struct damos_access_pattern pattern = {
> + /* Find regions having PAGE_SIZE or larger size */
> + .min_sz_region = PAGE_SIZE,
> + .max_sz_region = ULONG_MAX,
> + /* and accessed for more than the threshold */
This comment would be better to be written again?
> + .min_nr_accesses = 0,
> + .max_nr_accesses = 0,
If we're gonna set above two fields anyway later, we could simply remove above
three lines.
> + /* no matter its age */
> + .min_age_region = 0,
> + .max_age_region = UINT_MAX,
> + };
> struct damos_quota quota = damon_lru_sort_quota;
>
> /* Use half of total quota for hot/cold pages sorting */
> quota.ms = quota.ms / 2;
>
> + switch (action) {
> + case DAMOS_LRU_PRIO:
> + pattern.min_nr_accesses = thres;
> + pattern.max_nr_accesses = UINT_MAX;
> + break;
> + case DAMOS_LRU_DEPRIO:
> + pattern.min_age_region = thres;
> + break;
> + default:
> + return NULL;
> + }
> +
This switch-case makes me wondering if the 'default' case really possible case.
I think it would be clearer to set these from caller.
IMHO, it might be clearer and shorter to define a static global 'struct
damos_access_pattern' stub variable, and make the
damon_lru_sort_new_{hot,cold}_scheme() copies it to their local variable,
update the relevant fields, and pass that to 'damon_new_scheme()'. What do you
think?
> return damon_new_scheme(
> /* find the pattern, and */
> - pattern,
> + &pattern,
> /* (de)prioritize on LRU-lists */
> action,
> /* under the quota. */
> @@ -157,37 +180,13 @@ static struct damos *damon_lru_sort_new_scheme(
> /* Create a DAMON-based operation scheme for hot memory regions */
> static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
> {
> - struct damos_access_pattern pattern = {
> - /* Find regions having PAGE_SIZE or larger size */
> - .min_sz_region = PAGE_SIZE,
> - .max_sz_region = ULONG_MAX,
> - /* and accessed for more than the threshold */
> - .min_nr_accesses = hot_thres,
> - .max_nr_accesses = UINT_MAX,
> - /* no matter its age */
> - .min_age_region = 0,
> - .max_age_region = UINT_MAX,
> - };
> -
> - return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
> + return damon_lru_sort_new_scheme(hot_thres, DAMOS_LRU_PRIO);
If we follow what I suggested above, we could make this like below:
struct damos_access_pattern pattern = damon_lru_sort_stub_access_pattern;
pattern.min_nr_accesses = hot_thres;
return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
> }
>
> /* Create a DAMON-based operation scheme for cold memory regions */
> static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
> {
> - struct damos_access_pattern pattern = {
> - /* Find regions having PAGE_SIZE or larger size */
> - .min_sz_region = PAGE_SIZE,
> - .max_sz_region = ULONG_MAX,
> - /* and not accessed at all */
> - .min_nr_accesses = 0,
> - .max_nr_accesses = 0,
> - /* for min_age or more micro-seconds */
> - .min_age_region = cold_thres,
> - .max_age_region = UINT_MAX,
> - };
> -
> - return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
> + return damon_lru_sort_new_scheme(cold_thres, DAMOS_LRU_DEPRIO);
And similarly here.
> }
>
> static int damon_lru_sort_apply_parameters(void)
> --
> 2.31.0
>
>
Thanks,
SJ
