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Message-ID: <20200618134142.GD3346@MiWiFi-R3L-srv>
Date: Thu, 18 Jun 2020 21:41:42 +0800
From: Baoquan He <bhe@...hat.com>
To: Nitin Gupta <nigupta@...dia.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Nitin Gupta <ngupta@...ingupta.dev>,
Luis Chamberlain <mcgrof@...nel.org>,
Kees Cook <keescook@...omium.org>,
Iurii Zaikin <yzaikin@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
open list <linux-kernel@...r.kernel.org>,
"open list:PROC SYSCTL" <linux-fsdevel@...r.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: [PATCH] mm: Use unsigned types for fragmentation score
On 06/17/20 at 06:03pm, Nitin Gupta wrote:
> Proactive compaction uses per-node/zone "fragmentation score" which
> is always in range [0, 100], so use unsigned type of these scores
> as well as for related constants.
>
> Signed-off-by: Nitin Gupta <nigupta@...dia.com>
> ---
> include/linux/compaction.h | 4 ++--
> kernel/sysctl.c | 2 +-
> mm/compaction.c | 18 +++++++++---------
> mm/vmstat.c | 2 +-
> 4 files changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
> index 7a242d46454e..25a521d299c1 100644
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -85,13 +85,13 @@ static inline unsigned long compact_gap(unsigned int order)
>
> #ifdef CONFIG_COMPACTION
> extern int sysctl_compact_memory;
> -extern int sysctl_compaction_proactiveness;
> +extern unsigned int sysctl_compaction_proactiveness;
> extern int sysctl_compaction_handler(struct ctl_table *table, int write,
> void *buffer, size_t *length, loff_t *ppos);
> extern int sysctl_extfrag_threshold;
> extern int sysctl_compact_unevictable_allowed;
>
> -extern int extfrag_for_order(struct zone *zone, unsigned int order);
> +extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
> extern int fragmentation_index(struct zone *zone, unsigned int order);
> extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
> unsigned int order, unsigned int alloc_flags,
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 58b0a59c9769..40180cdde486 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2833,7 +2833,7 @@ static struct ctl_table vm_table[] = {
> {
> .procname = "compaction_proactiveness",
> .data = &sysctl_compaction_proactiveness,
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(sysctl_compaction_proactiveness),
Patch looks good to me. Wondering why not using 'unsigned int' here,
just curious.
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = SYSCTL_ZERO,
> diff --git a/mm/compaction.c b/mm/compaction.c
> index ac2030814edb..45fd24a0ea0b 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -53,7 +53,7 @@ static inline void count_compact_events(enum vm_event_item item, long delta)
> /*
> * Fragmentation score check interval for proactive compaction purposes.
> */
> -static const int HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500;
> +static const unsigned int HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500;
>
> /*
> * Page order with-respect-to which proactive compaction
> @@ -1890,7 +1890,7 @@ static bool kswapd_is_running(pg_data_t *pgdat)
> * ZONE_DMA32. For smaller zones, the score value remains close to zero,
> * and thus never exceeds the high threshold for proactive compaction.
> */
> -static int fragmentation_score_zone(struct zone *zone)
> +static unsigned int fragmentation_score_zone(struct zone *zone)
> {
> unsigned long score;
>
> @@ -1906,9 +1906,9 @@ static int fragmentation_score_zone(struct zone *zone)
> * the node's score falls below the low threshold, or one of the back-off
> * conditions is met.
> */
> -static int fragmentation_score_node(pg_data_t *pgdat)
> +static unsigned int fragmentation_score_node(pg_data_t *pgdat)
> {
> - unsigned long score = 0;
> + unsigned int score = 0;
> int zoneid;
>
> for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
> @@ -1921,17 +1921,17 @@ static int fragmentation_score_node(pg_data_t *pgdat)
> return score;
> }
>
> -static int fragmentation_score_wmark(pg_data_t *pgdat, bool low)
> +static unsigned int fragmentation_score_wmark(pg_data_t *pgdat, bool low)
> {
> - int wmark_low;
> + unsigned int wmark_low;
>
> /*
> * Cap the low watermak to avoid excessive compaction
> * activity in case a user sets the proactivess tunable
> * close to 100 (maximum).
> */
> - wmark_low = max(100 - sysctl_compaction_proactiveness, 5);
> - return low ? wmark_low : min(wmark_low + 10, 100);
> + wmark_low = max(100U - sysctl_compaction_proactiveness, 5U);
> + return low ? wmark_low : min(wmark_low + 10, 100U);
> }
>
> static bool should_proactive_compact_node(pg_data_t *pgdat)
> @@ -2604,7 +2604,7 @@ int sysctl_compact_memory;
> * aggressively the kernel should compact memory in the
> * background. It takes values in the range [0, 100].
> */
> -int __read_mostly sysctl_compaction_proactiveness = 20;
> +unsigned int __read_mostly sysctl_compaction_proactiveness = 20;
>
> /*
> * This is the entry point for compacting all nodes via
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 3e7ba8bce2ba..b1de695b826d 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1079,7 +1079,7 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
> * It is defined as the percentage of pages found in blocks of size
> * less than 1 << order. It returns values in range [0, 100].
> */
> -int extfrag_for_order(struct zone *zone, unsigned int order)
> +unsigned int extfrag_for_order(struct zone *zone, unsigned int order)
> {
> struct contig_page_info info;
>
> --
> 2.27.0
>
>
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