lkml.org 
[lkml]   [2023]   [Dec]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH V4 1/2] mm: add defines for min/max swappiness
From

在 2023/12/13 9:38, Dan Schatzberg 写道:
> [????????? schatzberg.dan@gmail.com ????????? https://aka.ms/LearnAboutSenderIdentification,????????????]
>
> We use the constants 0 and 200 in a few places in the mm code when
> referring to the min and max swappiness. This patch adds MIN_SWAPPINESS
> and MAX_SWAPPINESS #defines to improve clarity. There are no functional
> changes.
>
> Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
> ---
> include/linux/swap.h | 2 ++
> mm/memcontrol.c | 2 +-
> mm/vmscan.c | 10 +++++-----
> 3 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index f6dd6575b905..e2ab76c25b4a 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -407,6 +407,8 @@ extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
>
> #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
> #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
> +#define MIN_SWAPPINESS 0
> +#define MAX_SWAPPINESS 200

Do MAX_SWAPPINESS apply for all swapppiness? If so, maybe better change
swappiness sysctl define:
```
sysctl.c:

{
        .procname    = "swappiness",
        .data        = &vm_swappiness,
        .maxlen        = sizeof(vm_swappiness),
        .mode        = 0644,
        .proc_handler    = proc_dointvec_minmax,
        .extra1        = SYSCTL_ZERO,
        .extra2        = SYSCTL_TWO_HUNDRED,
    },

```

Here hard code swappiness in [0, 200], and now add a new define.

And many other code hard reference 200 into max value of swappiness, like:

```
memcontrol.c:
static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
                       struct cftype *cft, u64 val)
{
    struct mem_cgroup *memcg = mem_cgroup_from_css(css);

    if (val > 200)
        return -EINVAL;

    if (!mem_cgroup_is_root(memcg))
        memcg->swappiness = val;
    else
        vm_swappiness = val;

    return 0;
}
vmscan.c:

/*
 * From 0 .. 200.  Higher means more swappy.
 */
int vm_swappiness = 60;

```


> extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
> unsigned long nr_pages,
> gfp_t gfp_mask,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1c1061df9cd1..9748a6b88bb8 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4337,7 +4337,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
> {
> struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>
> - if (val > 200)
> + if (val > MAX_SWAPPINESS)
> return -EINVAL;
>
> if (!mem_cgroup_is_root(memcg))
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 506f8220c5fe..2aa671fe938b 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2403,7 +2403,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
> ap = swappiness * (total_cost + 1);
> ap /= anon_cost + 1;
>
> - fp = (200 - swappiness) * (total_cost + 1);
> + fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);
> fp /= file_cost + 1;
>
> fraction[0] = ap;
> @@ -4400,7 +4400,7 @@ static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx
> {
> int type, tier;
> struct ctrl_pos sp, pv;
> - int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness };
> + int gain[ANON_AND_FILE] = { swappiness, MAX_SWAPPINESS - swappiness };
>
> /*
> * Compare the first tier of anon with that of file to determine which
> @@ -4444,7 +4444,7 @@ static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int sw
> type = LRU_GEN_ANON;
> else if (swappiness == 1)
> type = LRU_GEN_FILE;
> - else if (swappiness == 200)
> + else if (swappiness == MAX_SWAPPINESS)
> type = LRU_GEN_ANON;
> else
> type = get_type_to_scan(lruvec, swappiness, &tier);
> @@ -5368,9 +5368,9 @@ static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
>
> lruvec = get_lruvec(memcg, nid);
>
> - if (swappiness < 0)
> + if (swappiness < MIN_SWAPPINESS)
> swappiness = get_swappiness(lruvec, sc);
> - else if (swappiness > 200)
> + else if (swappiness > MAX_SWAPPINESS)
> goto done;
>
> switch (cmd) {
> --
> 2.34.1
>

\
 
 \ /
  Last update: 2023-12-13 02:58    [W:0.158 / U:0.140 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site