Re: [PATCH V3] mm/damon: simplify scheme create in lru_sort.c

[haoxin]

在 2022/9/15 下午9:25, SeongJae Park 写道:
> Hi Xin,
>
> On Thu, 15 Sep 2022 10:36:55 +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.
> >
> > Suggested-by: SeongJae Park <sj@xxxxxxxxxx>
> > Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
> > Changes from v2
> > (https://lore.kernel.org/linux-mm/20220914113859.37637-1-xhao@xxxxxxxxxxxxxxxxx/)
> > - Add static global 'struct damos_access_pattern' stub variable
> Chagelog should not be in the commit message area,
>
> > ---
> but here.
>
> >   mm/damon/lru_sort.c | 41 +++++++++++++++++++----------------------
> >   1 file changed, 19 insertions(+), 22 deletions(-)
> >
> > diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
> > index 07a0908963fd..6a26c5822286 100644
> > --- a/mm/damon/lru_sort.c
> > +++ b/mm/damon/lru_sort.c
> > @@ -132,6 +132,18 @@ DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat,
> >   		lru_sort_tried_cold_regions, lru_sorted_cold_regions,
> >   		cold_quota_exceeds);
> >
> > +struct damos_access_pattern damon_lru_sort_stub_access_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 looks inappropriate.  How about 'no matter its access frequency'?
>
> > +	.min_nr_accesses = 0,
> > +	.max_nr_accesses = UINT_MAX,
> > +	/* no matter its age */
> > +	.min_age_region = 0,
> > +	.max_age_region = UINT_MAX,
> > +};
> > +
> >   static struct damon_ctx *ctx;
> >   static struct damon_target *target;
> >
> > @@ -157,17 +169,9 @@ 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,
> > -	};
> > +	struct damos_access_pattern pattern = damon_lru_sort_stub_access_pattern;
> More than 80 columns.  Renaming stub_access_pattern into stub_pattern might
> make sense.
>
> > +
> > +	pattern.min_nr_accesses = hot_thres;
> >
> >   	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
> >   }
> > @@ -175,17 +179,10 @@ static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
> >   /* 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,
> > -	};
> > +	struct damos_access_pattern pattern = damon_lru_sort_stub_access_pattern;
> More than 80 columns.
>
> > +
> > +	pattern.max_nr_accesses = 0;
> > +	pattern.min_age_region = cold_thres;
> >
> >   	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
> >   }
> > --
> > 2.31.0
> Other than the trivial things, look good.  As my comments are only for trivial
> cosmetic things, I will make the change and post v4 on my own.
Ok,  thank you very much for such a detailed review.
> Thanks,
> SJ