Messages in this thread Patch in this message | | | Date | Wed, 13 Dec 2023 09:58:26 +0800 | Subject | Re: [PATCH V4 1/2] mm: add defines for min/max swappiness | From | Huan Yang <> |
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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 >
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